Channel saturation current test circuit

Abstract

The present specification provides a channel saturation current test circuit, comprising: a measurement module comprising a plurality of groups of drive circuits, the drive circuits are connected in parallel, each drive circuit comprises a measurement unit and an anti-backflow unit, one end of the measurement unit is connected with the anti-backflow unit, the other end of the measurement unit is connected to a high end of a power supply, and the other end of the measurement unit is connected to a high end of the power supply; the anti-backflow unit comprises a protective resistor, and the other end of the anti-backflow unit is connected with a tested element; and the suppression module is connected to the two ends of the tested element. The measuring range is enlarged by connecting the measuring circuit in parallel, a capacitor is connected in series at the DS end to suppress oscillation and achieve stable measurement, and a small resistor is connected in series on a pin to prevent current nonuniformity caused by contact.

Description

Technical Field

[0001] The present specification relates to the technical field of power device measurement, and in particular to a channel saturation current test circuit. Background Art

[0002] At present, the performance of traditional Si and GaAs semiconductor devices has approached the theoretical limit determined by the materials themselves. Semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) with wide bandgap have become ideal materials for the development of high-power, high-frequency, high-temperature and radiation-resistant electronic devices due to their advantages such as wide bandgap, high saturation drift velocity, and high critical breakdown electric field. The GaN material series has low heat generation rate and high breakdown electric field, which is suitable for the development of radiation-resistant, high-frequency, and high-density integrated electronic devices. Semi-insulating SiC single crystal materials have become the best substrate for the preparation of wide bandgap solid-state microwave devices due to their wide bandgap, high saturation drift velocity, high critical breakdown electric field, and high thermal conductivity.

[0003] Solid-state microwave power devices based on GaAs, GaN, and SiC materials have certain particularities compared to traditional depletion-mode devices (such as JFET devices). Their main application areas are RF and microwave fields. Due to defects in the material process mechanism, such as current collapse effect, self-heating effect, polarization effect, and thermal electron effect, the preparation process of GaAs, GaN, and SiC devices is complex, the cycle is long, and the price is expensive.

[0004] As the process size continues to shrink, very large scale integrated circuits (VLSI) have put forward new requirements for power supply parameters. For example, the core voltage of CPU, digital signal processing (DSP), and field programmable gate array (FPGA) has dropped sharply, and the power consumption current has increased sharply, requiring the enhanced gallium nitride power device as the power output stage to output as large an operating current as possible. However, the optimization of gallium nitride power device parameters is generally completed during the process manufacturing process, such as changing the doping, thickness, and Al composition of the device AlGaN barrier layer. After the enhancement p-type cap layer gallium nitride power device is packaged, its device parameters cannot be optimized, especially the saturated drain-source current parameter cannot be increased.

[0005] There are many electron or hole traps in the source, gate, drain and two-dimensional electron gas materials of GaN devices, and these traps will cause the performance parameters of GaN devices to change. In order to evaluate the impact of traps on GaN devices, it is necessary to quantify the changes in the performance parameters of GaN devices caused by these traps. The prior art measures the changes in the performance parameters of GaN devices caused by traps by adding a periodic voltage signal to the source or gate of the GaN device, and then obtains the defect parameters of the GaN device based on the changes in the performance parameters. However, many electron or hole traps will appear in the channel layer of the GaN device during epitaxy, and these traps capture electrons or holes, which will also cause changes in the performance parameters of the GaN device. Therefore, the defect parameters of the GaN device cannot be accurately measured by the methods of the prior art.

[0006] The existing technology mostly directly connects the measuring instrument to the measured component, first applies voltage through the high end and low end of the gate power supply to open the channel of the GaN device, and then applies voltage through the low end and high end of the power supply to measure the channel saturation current. The measurement circuit is mostly that the high end of the power supply is directly connected to the drain of the measured component through an ammeter, the low end of the power supply and the low end of the gate power supply are directly connected to the source of the measured component, and the high end of the gate power supply is connected to the gate of the measured component.

[0007] However, the existing measurement circuit is limited by only a single measurement unit, and the maximum measurement current is only 10A, which cannot cover the high-voltage products in the current usage environment and is restrictive. Moreover, when the drain voltage of the GaN device exceeds a certain value, as the drain voltage increases, the current will begin to decrease and cannot reach the ideal value. This is the device oscillation caused by the GaN current collapse, which makes it impossible to accurately measure the channel saturation current and obtain an accurate channel saturation current value, affecting the parameter measurement of the GaN device. Utility Model Content

[0008] In order to overcome the problems existing in the related art, this specification provides a channel saturation current test circuit.

[0009] According to one aspect of the utility model, a channel saturation current test circuit is provided, comprising:

[0010] The measuring module includes several groups of driving circuits, which are connected in parallel. The driving circuits include a measuring unit and an anti-backflow unit. One end of the measuring unit is connected to the anti-backflow unit, and the other end of the measuring unit is connected to the high end of the power supply. The anti-backflow unit includes a protective resistor, and the other end of the anti-backflow unit is connected to the measured component; the suppression module is connected to both ends of the measured component. The safety of the test circuit is ensured by setting the anti-backflow unit, and multiple groups of driving circuits are provided. The channel saturation current is shunted by connecting the driving circuits in parallel, so as to increase the maximum value of the channel saturation current that can be tested, so as to achieve current measurement greater than 10A.

[0011] In some embodiments, the anti-backflow unit is a diode, the anode of the diode is connected to the high end of the power supply through the measuring unit, and the cathode of the diode is connected to one end of the protection resistor. The diode is mainly used to prevent current backflow between power supplies.

[0012] In some embodiments, the other end of the anti-backflow unit is connected to the measured element through the drain pad; the measurement module includes four drive circuits, and the single drive circuit includes two pins connected to the drain pad, and the pins are in parallel. This arrangement allows the four measurement units to measure the sum of eight-channel currents, increasing the current measurement range, so that the circuit can be applied to high-voltage products, and expanding the scope of application.

[0013] In some embodiments, the power supplies operate simultaneously.

[0014] In some embodiments, the suppression module is a capacitor, and its two ends are respectively connected to the source and drain of the measured element. The series capacitor between the source and the drain can suppress the oscillation of the GaN device caused by excessive dv / dt, and can make the process of measuring the channel saturation current more stable, thereby improving the accuracy of measuring the parameters of the measured element.

[0015] In some embodiments, the gate of the device under test is connected to a high end of a gate power supply, and the source of the device under test is connected to a low end of a gate power supply. The high end of the gate power supply and the low end of the gate power supply are used to pressurize the device under test when the channel is opened.

[0016] In some embodiments, the circuit further includes a power supply low end and a source pad, wherein the power supply low end is connected to the source pad via a current limiting resistor, and the source pad is connected to the component under test. The current limiting resistor avoids circuit overload caused by excessive current, and can increase the test range of the test circuit.

[0017] In some embodiments, the current limiting resistors are connected in parallel in pairs, and the two ends are connected to the pins of the source pad and the low end of the power supply respectively; the number of the current limiting resistors is the same as the number of the protection resistors. The low end of the power supply corresponds to the high end of the power supply one by one, and is used to pressurize the measured component during measurement.

[0018] In some embodiments, the measuring units are respectively a first ammeter, a second ammeter, a third ammeter, and a fourth ammeter, and the channel saturation current of the measured element is the sum of the currents measured by the ammeters. The code forces each power supply to work simultaneously, and the current passing through each ammeter is measured, and finally the sum is calculated to calculate the channel saturation current passing through the measured element.

[0019] In some embodiments, the channel saturation current measurement range of the measured element is 0-80 A. The maximum channel saturation current measurement range of 80 A has basically covered all HV products, enabling the wide application of the circuit and greatly improving the scope of application of the circuit.

[0020] The utility model has the advantages of increasing the measuring range by connecting the measuring circuit in parallel, suppressing the oscillation by connecting the capacitor in series at the DS end to realize stable measurement, and preventing the current unevenness caused by contact by connecting a small resistor in series at the pin needle.

[0021] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the specification and, together with the description, serve to explain the principles of the specification.

[0023] Figure 1 It is a circuit diagram of the technical solution adopted in the prior art;

[0024] Figure 2 It is a circuit diagram of a channel saturation current test circuit according to an exemplary embodiment of the utility model;

[0025] In the figure: 1. measurement module, 11. first drive circuit, 12. second drive circuit, 13. third drive circuit, 14. fourth drive circuit, 2. suppression module. DETAILED DESCRIPTION

[0026] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this specification. The singular forms of "a", "said" and "the" used in this specification and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0027] It should be understood that although the terms first, second, third, etc. may be used in this specification to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this specification, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0028] Gallium nitride has a wide bandgap and good thermal conductivity, which allows it to match smaller transformers and high-power inductors, making chargers using gallium nitride technology smaller and more portable. Gallium nitride chargers can achieve fast charging while maintaining high efficiency and low-temperature working conditions, and are safer. Gallium nitride materials have a high critical field strength, so gallium nitride power devices have the characteristics of high withstand voltage. Gallium nitride transistors can still maintain good performance at high temperatures and are suitable for high power density and high frequency application scenarios. Gallium nitride transistors have good corrosion resistance and are suitable for use in harsh environments. Gallium nitride has the characteristics of high efficiency, low heat generation, safety and reliability. It uses advanced semiconductor materials and uses gallium nitride as the main process technology. It has a smaller size and lighter weight, so it has been widely used. However, there are many electron or hole traps in the source, gate, drain and two-dimensional electron gas materials of gallium nitride devices, which will cause the performance parameters of gallium nitride devices to change. In order to evaluate the impact of traps on gallium nitride devices, it is necessary to quantify the changes in the performance parameters of gallium nitride devices caused by these traps. The prior art measures the change in the performance parameters of the GaN device caused by traps by adding a periodic voltage signal to the source or gate of the GaN device, and then obtains the defect parameters of the GaN device based on the change in the performance parameters. However, many electron or hole traps will appear in the channel layer of the GaN device during epitaxy. These traps capture electrons or holes and also cause changes in the performance parameters of the GaN device. Therefore, the defect parameters of the GaN device cannot be accurately measured using the prior art methods. Figure 1As shown, in most existing measurement circuits, the high-end power supply FH1 is directly connected to the drain of the measured component GaN through an ammeter A, the low-end power supply FL1 and the low-end gate power supply GFL are directly connected to the source of the measured component GaN, and the high-end gate power supply GFH is connected to the gate of the measured component GaN.

[0029] During the test, the measuring instrument is directly connected to the GaN component under test. The high-end gate power supply GFH and the low-end gate power supply GFL are first applied to open the channel of the GaN component under test. Then, the channel saturation current is measured by applying voltage through the low-end power supply FL1 and the high-end power supply FH1.

[0030] The above measurement circuit is limited by only a single measurement unit, and the maximum measurement current is only 10A, which cannot cover the high-voltage products in the current usage environment and is restrictive. Moreover, when the drain voltage of the GaN device exceeds a certain value, as the drain voltage increases, the current will begin to decrease and cannot reach the ideal value. This is the device oscillation caused by the GaN current collapse, which makes it impossible to accurately measure the channel saturation current and obtain an accurate channel saturation current value, affecting the parameter measurement of the GaN device.

[0031] Next, the embodiments of this specification are described in detail.

[0032] like Figure 2 As shown, Figure 2 is a circuit diagram of a circuit shown in this specification according to an exemplary embodiment, including:

[0033] The measuring module 1 includes a plurality of driving circuits connected in parallel, wherein the driving circuits include a measuring unit and an anti-backflow unit, wherein one end of the measuring unit is connected to one end of the anti-backflow unit, and the other end of the measuring unit is connected to the high-end power supply FH1, FH2, FH3, and FH4, and the anti-backflow unit includes a protective resistor, and the other end of the anti-backflow unit is connected to the measured component through a drain pad;

[0034] The suppression module 2 is connected to both ends of the GaN component under test. The anti-backflow unit can be a diode D1, D2, D3, and D4. The positive electrodes of the diodes D1, D2, D3, and D4 are connected to the high-end power supply FH1, FH2, FH3, and FH4 through the measurement unit, and the negative electrodes of the diodes D1, D2, D3, and D4 are connected to the protection resistor. The function of the high-end power supply FH1, FH2, FH3, and FH4 running simultaneously is realized through code.

[0035] In some embodiments, the measurement module 1 includes four groups of driving circuits: a first driving circuit 11, a second driving circuit 12, a third driving circuit 13, and a fourth driving circuit 14. A single driving circuit includes two pins connected to the drain pad Drain Pad, and the pins are in parallel. The gate of the measured component GaN is connected to the high end GFH of the gate power supply, and the source of the measured component GaN is connected to the low end GFL of the gate power supply. The measuring unit A can be or include a first ammeter, a second ammeter, a third ammeter, and a fourth ammeter. The first ammeter is located in the first driving circuit 11, the second ammeter is located in the second driving circuit 12, the third ammeter is located in the third driving circuit 13, and the fourth ammeter is located in the fourth driving circuit 14. Each driving circuit is provided with a diode D1, D2, D3, D4, which is used to protect the driving circuit and avoid the reverse current backflow phenomenon, thereby improving the safety of the test circuit. The diodes D1, D2, D3, D4 are located between the measuring unit A and the protection resistor R. Even when the current backflow phenomenon occurs, the reverse current can be prevented from passing through and then reversely breaking through the ammeter, causing property loss.

[0036] Suppression module 2 is a capacitor, and the two ends of the capacitor are respectively connected to the source and drain of the GaN component under test. The suppression capacitor can suppress the oscillation of the GaN device caused by excessive dv / dt to achieve stable measurement of the channel saturation current. The function of the capacitor is to prevent voltage mutations and absorb overvoltages in the peak state. The series resistor acts as a damper, and the resistor consumes the energy of the overvoltage, thereby suppressing the oscillation of the circuit. The oscillation of this circuit is mainly due to the parasitic effect of the gate. For applications using GaN devices, the oscillation will be more serious due to the high switching frequency, especially when multiple devices are connected in parallel, forming multiple resonant cavities. The conventional method of reducing parasitic inductance through PCB routing optimization may not fully meet the requirements, so the parallel suppression module is used to suppress the oscillation of the component under test due to the increase in input voltage, and improve the measurement accuracy of the channel saturation current of the component under test.

[0037] This circuit also includes power low ends FL1, FL2, FL3, FL4 and source pad Source Pad. The power low ends FL1, FL2, FL3, FL4 are connected to the source pad Source Pad through current limiting resistors R, and the source pad Source Pad is connected to the component under test GaN. The current limiting resistors R are connected in parallel, and the two ends of the current limiting resistors R are respectively connected to the pins of the source pad Source Pad and the power low ends FL1, FL2, FL3, FL4; the number of current limiting resistors R is the same as the number of protection resistors. The gate of the component under test GaN is connected to the gate power high end GFH, and the source of the component under test GaN is connected to the gate power low end GFL, which is used to provide voltage when the channel of the component under test is turned on.

[0038] The measurement steps are as follows. First, the high end and the low end of the gate power supply are powered on to open and conduct the channel of the component under test and enter the on state. At this time, FH1-FH4 and FL1-FL4 are powered on at the same time through the code to force each circuit to work at the same time and test the component under test. At this time, the first ammeter measures the current I1 passing through the first drive circuit, the second ammeter measures the current I2 passing through the second drive circuit, the third ammeter measures the current I3 passing through the third drive circuit, and the fourth ammeter measures the current I4 passing through the fourth drive circuit. Then, according to the circuit principle, it can be obtained that the channel saturation current passing through the component under test is the sum of the currents of each branch, that is, the channel saturation current IDsat=I1+I2+I3+I4.

[0039] In this embodiment, each individual drive circuit is connected to the measuring fixture through two pins, with a total of 8 pins, which increases the measurement range of the channel saturation current, and a high-power protection resistor is connected in series on each pin, which can prevent uneven pin current caused by contact, and prevent excessive current density at individual points from damaging the device or inaccurate measurement. The measurement unit is connected in parallel to shunt, so the maximum measurement voltage is 8*10A=80A, which is enough to cover high-voltage products and achieve the measurement of static channel saturation current greater than 10A.

[0040] In the attached drawings of this embodiment, FH1 is the high end of the first power supply, FH2 is the high end of the second power supply, FH3 is the high end of the third power supply, FH4 is the high end of the fourth power supply, FL1 is the low end of the first power supply, FL2 is the low end of the second power supply, FL3 is the low end of the third power supply, FL4 is the low end of the fourth power supply, GFH is the high end of the gate power supply, and GFL is the low end of the gate power supply; R in the measurement module 1 is a protection resistor, A is an ammeter, D1 is a first diode, D2 is a second diode, D3 is a third diode, D4 ​​is a fourth diode, I1 is a current passing through the first drive circuit, I2 is a current passing through the second drive circuit, I3 is a current passing through the third drive circuit, I4 is a current passing through the fourth drive circuit, and C in the suppression module 2 is a suppression capacitor; Drain PAD is a drain pad, Source PAD is a source pad, GaN is a measured element (gallium nitride), and the current limiting resistor is connected to the low end of the power supply.

[0041] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0042] Those skilled in the art will readily appreciate other embodiments of the specification after considering the specification and practicing the utility model claimed herein. The specification is intended to cover any variations, uses or adaptations of the specification that follow the general principles of the specification and include common knowledge or customary techniques in the art that are not claimed in the specification. The specification and examples are to be considered exemplary only, and the true scope and spirit of the specification are indicated by the following claims.

[0043] It should be understood that the present description is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present description is limited only by the appended claims.

[0044] The above description is only a preferred embodiment of this specification and is not intended to limit this specification. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this specification should be included in the scope of protection of this specification.

Claims

1. A channel saturation current test circuit, characterized in that: include: A measuring module, comprising a plurality of drive circuits, the drive circuits being connected in parallel, the drive circuit comprising a measuring unit and an anti-backflow unit, one end of the measuring unit being connected to one end of the anti-backflow unit, the other end of the measuring unit being connected to a high end of a power supply, the anti-backflow unit comprising a protective resistor, and the other end of the anti-backflow unit being connected to a measured element; The suppression module is connected to both ends of the measured element.

2. A channel saturation current test circuit according to claim 1, characterized in that: The anti-backflow unit is a diode, the anode of the diode is connected to the high end of the power supply through the measuring unit, and the cathode of the diode is connected to the protection resistor.

3. A channel saturation current test circuit according to claim 1, characterized in that: The other end of the anti-backflow unit is connected to the measured component through the drain pad; the measurement module includes four drive circuits, and a single drive circuit includes two pins connected to the drain pad, and the pins are in parallel relationship.

4. A channel saturation current test circuit according to claim 3, characterized in that: A plurality of said power supply high ends operate simultaneously.

5. A channel saturation current test circuit according to claim 1, characterized in that: The suppression module is a capacitor, and two ends of the capacitor are respectively connected to the source and drain of the measured element.

6. A channel saturation current test circuit according to claim 1, characterized in that: The gate of the measured element is connected to a high end of a gate power supply, and the source of the measured element is connected to a low end of the gate power supply.

7. A channel saturation current test circuit according to claim 1, characterized in that: The channel saturation current test circuit also includes a power supply low end and a source pad, the power supply low end is connected to the source pad through a current limiting resistor, and the source pad is connected to the component under test.

8. A channel saturation current test circuit according to claim 7, characterized in that: The current limiting resistors are connected in parallel in pairs, and the two ends of the current limiting resistors are respectively connected to the pins of the source pad and the low end of the power supply; The number of the current limiting resistors is the same as the number of the protection resistors.

9. A channel saturation current test circuit according to claim 3, characterized in that: The measuring unit comprises a first ammeter, a second ammeter, a third ammeter and a fourth ammeter, and the channel saturation current of the measured element is the sum of the currents measured by the ammeters.

10. The channel saturation current test circuit according to claim 1, characterized in that: The channel saturation current measurement range of the measured element is 0-80A.

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