CN102955112B - Method for pre-screening direct-current steady-state power aging of GaN-based device - Google Patents

Abstract

The invention discloses a method for pre-screening the DC steady-state power aging of a GaN-based device, comprising: packaging and testing the GaN-based device to determine the DC steady-state power of the GaN-based device to be tested; using microscopic infrared The thermal imager measures the junction temperature of the device, and mathematically fits the measured junction temperature to obtain the relationship between the peak junction temperature of the GaN-based device under test and the DC steady-state power, and determines the DC steady-state power of the GaN-based device under test. Conditions of power aging; perform DC steady-state power aging on the GaN-based device under test, and obtain the change curve of each characteristic parameter of the GaN-based device under test with time; determine the device according to the change curve of each characteristic parameter of the GaN-based device with time. The threshold time for each characteristic parameter to become stable determines the time for the device to undergo DC steady-state aging; perform aging screening on multiple GaN-based devices to be tested, and eliminate devices whose device characteristic parameters are difficult to stabilize within the threshold time Prescreening of DC Steady-State Power Aging of Devices.

Description

A method for pre-screening DC steady-state power aging of GaN-based devices

technical field

The invention relates to the technical field of DC steady-state power aging, in particular to a method for pre-screening the DC steady-state power aging of GaN-based devices.

Background technique

Steady-state power aging is to continuously apply a certain electrical stress to the device for a long period of time, and accelerate various physical and chemical processes inside the device through the comprehensive action of electricity and heat, so as to promote the early exposure of various potential defects inside the device, so as to achieve the elimination purpose of early failure devices. It has a good screening effect on a series of defects that may exist in the process, such as surface contamination, channel leakage, chip cracks, and oxide layer defects.

The reliability of semiconductor devices is usually represented by an idealized curve of the bathtub curve, which consists of 3 regions. In the first region, the failure rate decreases with time, called the early failure period. In the second region, the failure rate reaches a constant value, which is called the constant failure rate period or service life region. In the third region, the failure rate increases with time, known as the wear-out period. In the first region, that is, the early failure period, the device parameters are unstable and the device failure rate is high. Afterwards, the device parameters tend to be stable in the period of constant failure rate. The point in time between the early failure period and the constant failure rate period is generally referred to as the threshold time. In the process of steady-state DC power aging of devices, determining the threshold time between the early failure period and the service life of the device as a basis for pre-screening of devices can greatly save the time for steady-state DC aging, and can Ensure that the device reaches a stable service life after pre-screening, increasing the stability of the device during use.

The most critical issue in screening GaN-based power devices using the electrical power aging method is to determine the stress conditions for steady-state power aging screening of devices. If the stress conditions are too low, the screening effect will not be achieved, and if the stress conditions are too high, the temperature may exceed the maximum allowable junction temperature. resulting in overstress failure. In order to achieve the best screening effect, the steady-state power aging of the device is carried out under the limit power consumption condition that the device can bear. The relationship between the power dissipated by the device, and then determine the stress conditions for the device to undergo steady-state power aging screening.

Contents of the invention

(1) Technical problems to be solved

To achieve the above purpose, the main purpose of the present invention is to provide a method for pre-screening the DC steady-state power aging of GaN-based devices.

(2) Technical solutions

In order to achieve the above object, the present invention provides a method for pre-screening the DC steady-state power aging of GaN-based devices, the method comprising:

Carry out packaging test on the tested GaN-based device, and determine the DC steady-state power of the tested GaN-based device;

Measure the junction temperature of the tested GaN-based device with a microscopic infrared thermal imager, and mathematically fit the measured junction temperature to obtain the relationship between the peak junction temperature of the tested GaN-based device and the DC steady-state power, and determine the measured Measure the conditions for DC steady-state power aging of GaN-based devices and the conditions of the ambient temperature during aging;

Under the condition that the measured GaN-based device is subjected to DC steady-state power aging, the measured GaN-based device is subjected to DC steady-state power aging, and the change curve of each characteristic parameter of the measured GaN-based device with time is obtained;

Determining the threshold time for each characteristic parameter of the device to stabilize from the time-varying curve of each characteristic parameter of the measured GaN-based device; and

Aging screening is performed on multiple GaN-based devices to be tested, and devices whose device characteristic parameters are difficult to stabilize within the threshold time are eliminated, so as to realize pre-screening of DC steady-state power aging of GaN-based devices.

In the above scheme, the packaging test of the GaN-based device under test and the determination of the DC steady-state power of the GaN-based device under test include: first fixing the GaN-based device under test on a fixture, which has a function for suppressing and Eliminate the self-oscillating circuit of the GaN-based device under test, and then use a DC power supply to measure the DC characteristics of the GaN-based device under test, and obtain the leakage voltage and current of the GaN-based device under different gate voltages. The leakage voltage and the leakage current are multiplied to obtain the DC steady-state power of the GaN-based device under test.

In the above scheme, the junction temperature of the GaN-based device under test is measured with a microscopic infrared thermal imager, and the measured junction temperature is mathematically fitted to obtain the peak junction temperature of the GaN-based device under test and the DC steady-state power. The relationship between the measured GaN-based devices to determine the DC steady-state power aging conditions and the ambient temperature conditions during aging, including: using a microscopic infrared thermal imager to measure the junction temperature of the GaN-based device under test, and obtain the tested GaN-based device Measure the junction temperature distribution and peak junction temperature of GaN-based devices, and then use the Origin software to mathematically simulate the measured junction temperature distribution and peak junction temperature to obtain the peak junction temperature and DC steady-state power of the device and the peak junction temperature The relationship curve between the device and the ambient temperature of the device, and then determine the conditions for the DC steady-state power aging of the GaN-based device under test based on the relationship curve.

In the above scheme, the use of a microscopic infrared thermal imager to measure the junction temperature of the GaN-based device under test, to obtain the junction temperature distribution and peak junction temperature of the GaN-based device under test, includes: the microscopic infrared thermal imager sets the fixture to The temperature of the device is controlled at 70°C; the device packaged in a single tube is installed on the fixture, and the fixture suppresses the self-excited oscillation of the device through the suppression oscillation circuit, and outputs the DC steady-state power of the device; the microscopic infrared thermal imager passes through the detection chip The distribution of radiant energy density is converted into the temperature value of each point on the surface by computer software, and the junction temperature distribution and peak junction temperature of the measured GaN-based device are determined.

In the above scheme, the condition for determining the DC steady-state power aging of the measured GaN-based device from the relationship curve is to determine the ambient temperature of the measured GaN-based device when it is subjected to DC steady-state power aging, that is, the temperature of the substrate, leakage Terminal voltage and drain terminal current, wherein the temperature of the substrate is determined by micro-infrared method, and the drain terminal voltage and drain terminal current are obtained by measuring the DC characteristics of the GaN-based device under test with a DC power supply.

In the above scheme, the condition for determining the DC steady-state power aging of the GaN-based device under test from the relational curve includes: the leakage voltage and leakage current of the GaN-based device under test under different gate voltages obtained from the measurement are obtained by calculating The DC power of the measured GaN-based device; the mathematical relationship curve between the peak junction temperature and the corresponding DC steady-state power is obtained through the mathematical analysis software of Origin; the peak junction temperature of the device under different ambient temperatures is obtained from the results obtained at different substrate temperatures. The relationship between temperature and DC steady state power.

In the above scheme, the conditions for the DC steady-state power aging of the measured GaN-based device include: using a microscopic infrared thermal imager to measure the junction temperature distribution of the device, and the ambient temperature is controlled at 70°C. Since the junction temperature reaches Tjm And work continuously, the junction temperature distribution of the device at low voltage and small power consumption may become extremely uneven at high voltage and high power consumption, and obvious hot spots will appear, and even cause the device to fail. The influence of junction temperature and thermal resistance is small, so when drafting the screening conditions, it should be carried out under the conditions of increasing the ambient temperature of the device, reducing the power dissipation and reducing the drain voltage of the added device, so the measured GaN-based device is lower than 175°C Under the conditions of the junction temperature, the ambient temperature is 70°C, the bias conditions are drain voltage Vd=25V, and drain current Id=200mA.

In the above solution, the characteristic parameters of the measured GaN-based device include: drain current, threshold voltage, transconductance, Schottky turn-on voltage and reverse leakage current of the device.

In the above scheme, the threshold time for each characteristic parameter of the device to be stable is determined from the variation curve of each characteristic parameter of the measured GaN-based device with time, which is determined by the variation curve of each characteristic parameter of the measured GaN-based device with time Determine the time when the measured GaN-based device characteristic parameters tend to be stable, and determine the time to become stable as the threshold time for the measured GaN-based device parameters to stabilize and enter the steady-state aging working area.

In the above solution, when aging screening is performed on multiple GaN-based devices under test, the multiple GaN-based devices under test are GaN-based devices of the same batch.

(3) Beneficial effects

As can be seen from the foregoing technical solutions, the present invention has the following beneficial effects:

1. The method for pre-screening the DC steady-state power aging of GaN-based devices provided by the present invention is to determine the stress conditions of GaN device DC steady-state power aging through the microscopic infrared measurement method, and to determine the DC steady-state power under the determined DC steady-state power conditions. The device is aged for a certain period of time, and the time point when the device characteristic parameters tend to be stable is determined as the threshold time of the early failure period and stable service life of the device, and the devices that are difficult to achieve parameter stability within the threshold time are eliminated to realize GaN-based devices. Pre-screening of dc steady-state power aging.

2. The method for pre-screening the DC steady-state power aging of GaN-based devices provided by the present invention is used to determine the threshold time between the early failure period of the device and the constant failure rate period, and the same batch of characteristic parameters within this time interval The consistent devices are pre-screened, and the devices whose device parameters reach stability within the threshold time pass the screening, and the devices that are difficult to stabilize are eliminated, so as to realize the aging and pre-screening of the steady-state DC power of GaN-based HEMT devices. This method has important guiding significance for improving the stability of the device and evaluating the reliability of the device effectively.

Description of drawings

Fig. 1 is the flow chart of the method for pre-screening the DC steady-state power aging of GaN-based devices provided by the present invention;

Fig. 2 is the AlGaN/GaN HEMT device structure that adopts according to the embodiment of the present invention measurement; Wherein, Fig. 2 (a) is h device structure, Fig. 2 (b) is the device structure of 75n3;

Fig. 3 is a microscopic infrared image of a GaN device obtained by microscopic infrared measurement according to an embodiment of the present invention; wherein, Fig. 3(a) is the junction temperature distribution of the h device, and Fig. 3(b) is the junction temperature distribution of the 75n3 device picture;

Fig. 4 is the variation curve of the peak junction temperature of the device according to the mathematical analysis of the embodiment of the present invention with the DC steady-state power of the device;

Fig. 5 (a) is the curve according to the variation of Vd and Id of the TRI structure device of the embodiment of the present invention 1#10 with time;

Fig. 5 (b) is the curve according to the variation of Vg and Ig of the TRI structure device of the embodiment of the present invention 1#10 with time;

Fig. 6 (a) is according to the curve of the variation of Vd and Id of the TRI structure device of the embodiment of the present invention 1#10 with time;

Fig. 6(b) is a curve of Vg and Ig of the TRI structure device according to Example 1#10 of the present invention as a function of time.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

In the embodiment provided by the present invention, the reliability of the device is initially screened by conducting GaN/AlGaN HEMT DC steady-state power aging experiments. The method first uses a micro-infrared measurement method to obtain the relationship between the peak junction temperature and the DC steady-state power , so as to determine the steady-state aging conditions of the device (the working voltage, working current and the temperature of the substrate when the device is aging), and perform DC steady-state power aging on the device under a certain DC steady-state power aging condition according to the specific characteristics of the device .

The performance parameters of the device are unstable at the initial aging, and tend to be stable after a certain period of aging. For devices with good consistency, the time when the device parameters tend to be stable is roughly the same. This time is determined by DC steady-state power aging, and this time is determined as the early failure time of the device. For the same batch of devices, this method is used to pre-screen the devices. If the parameters of the device still cannot be stabilized after the early failure period, the device should be rejected.

The early failure period of the device is generally within 80-100 hours. Using this method for pre-screening of GaN devices not only realizes an aging process for the device so that the device parameters tend to be stable, but also realizes that the device can be used in a short period of time. The screening process avoids long-term aging and saves manpower and material resources.

The realization principle of the present invention is that the service life curve of the device is a bathtub curve, and in the period of early failure, the device parameters are unstable, and the failure rate of the device in the stable period is constant, and the parameters also tend to be stable, so the early failure period of the device is determined to be Helpful for an early screening of devices. Devices often contain defects that cause incipient failure. These devices can usually be identified through a screening process that usually involves applying excitation to the device and "burning in" the device for a period of time, after which a failure rate is basically determined. is a constant region. Therefore, this method provides an effective way to characterize the reliability of GaN devices. The pre-screening of GaN devices is realized by a simple and operable method.

The measurement of the peak junction temperature is the premise of formulating the screening stress of high-reliability devices. Device screening can reflect the actual reliability characteristics of the device under a certain power operation for the removal of early failure devices or devices with hidden dangers, so as to realize the effective control of device reliability. evaluate. Most of the steady-state working life tests of GaN-based HEMT devices are carried out under a certain case temperature and corresponding maximum rated power.

Calculate according to T _j =P R _th (jc)+T _c , where Tj is the peak junction temperature value of the GaN device, P is the DC dissipation power of the device, and R _th (jc) is the distance between the junction temperature of the device and the ambient temperature Thermal resistance, Tc is the ambient temperature of the device.

The junction temperature is measured by micro-infrared thermography, the quantitative relationship between power and peak junction temperature is obtained, and the stress conditions for steady-state aging of high-reliability devices are determined. Under this condition, a DC steady-state power stress is applied to GaN-based HEMT devices in a short period of time, and computer software is used to collect real-time curves of the device's characteristic parameters over time, and then determine the time when the device's characteristic parameters tend to be stable. The time for pre-screening of the device, so as to stabilize the characteristic parameters of the device and achieve the purpose of pre-screening.

Based on the above realization principle, Fig. 1 shows a flowchart of a method for pre-screening the DC steady-state power aging of GaN-based devices provided by the present invention, including the following steps:

Step 1: Carry out packaging test on the tested GaN-based device, and determine the DC steady-state power of the tested GaN-based device;

Step 2: Measure the junction temperature of the GaN-based device under test with a microscopic infrared camera, and perform mathematical fitting on the measured junction temperature to obtain the relationship between the peak junction temperature of the GaN-based device under test and the DC steady-state power , to determine the conditions for the DC steady-state power aging of the GaN-based device under test and the conditions of the ambient temperature during aging;

Step 3: Perform DC steady-state power aging on the measured GaN-based device under the condition that the measured GaN-based device is subjected to DC steady-state power aging, and obtain a time-varying curve of each characteristic parameter of the tested GaN-based device;

Step 4: Determine the threshold time for each characteristic parameter of the device to stabilize from the time-varying curve of each characteristic parameter of the measured GaN-based device;

Step 5: Aging screening is performed on multiple GaN-based devices to be tested, and devices whose device characteristic parameters are difficult to stabilize within the threshold time are eliminated, so as to realize pre-screening for DC steady-state power aging of GaN-based devices.

Wherein, the packaging test of the GaN-based device under test and the determination of the DC steady-state power of the GaN-based device under test include: first fixing the GaN-based device under test on a fixture, the fixture has a function for suppressing and eliminating the Measure the self-excited oscillation circuit of the GaN-based device, and then use a DC power supply to measure the DC characteristics of the GaN-based device under test, and obtain the leakage voltage and leakage current of the GaN-based device under different gate voltages. Multiplied by the leakage current to obtain the DC steady-state power of the GaN-based device under test. At the same time, the corresponding temperature conditions at this time are obtained.

The method is to measure the junction temperature of the measured GaN-based device by using a microscopic infrared thermal imager, and mathematically fit the measured junction temperature to obtain the relationship between the peak junction temperature of the measured GaN-based device and the DC steady-state power, Determine the conditions for the DC steady-state power aging of the tested GaN-based device and the conditions of the ambient temperature during aging, including: using a microscopic infrared thermal imager to measure the junction temperature of the tested GaN-based device to obtain the measured GaN-based device The junction temperature distribution and peak junction temperature of the device, and then use the Origin software to mathematically fit the measured junction temperature distribution and peak junction temperature to obtain the peak junction temperature of the device and the DC steady-state power and the relationship between the peak junction temperature and the device. A relationship curve between ambient temperatures, and then the relationship curve determines the conditions for the DC steady-state power aging of the GaN-based device under test.

The method of measuring the junction temperature of the measured GaN-based device with a microscopic infrared thermal imager to obtain the junction temperature distribution and peak junction temperature of the measured GaN-based device includes: the microscopic infrared thermal imager controls the temperature of the fixture at 70°C; the single-tube packaged device is installed on the fixture, the fixture suppresses the self-excited oscillation of the device through the oscillation suppression circuit, and outputs the DC steady-state power of the device; the microscopic infrared thermal imager detects the radiant energy density of the chip The distribution is converted into the temperature value of each point on the surface by computer software to determine the junction temperature distribution and peak junction temperature of the measured GaN-based device.

The condition for determining the DC steady-state power aging of the measured GaN-based device from the relationship curve is to determine the ambient temperature, that is, the temperature of the substrate, the drain terminal voltage and the drain voltage of the measured GaN-based device when the DC steady-state power is aged. Terminal current, wherein the temperature of the substrate is determined by micro-infrared method, and the drain terminal voltage and drain terminal current are obtained by measuring the DC characteristics of the GaN-based device under test with a DC power supply.

The condition for determining the DC steady-state power aging of the GaN-based device under test from the relational curve includes: the leakage voltage and leakage current of the GaN-based device under test under different gate voltages obtained from the measurement, and the measured GaN-based device is calculated and obtained. The DC power of the device; the mathematical relationship curve between the peak junction temperature and the corresponding DC steady-state power is obtained through the mathematical analysis software of Origin; the peak junction temperature and the DC steady-state power of the device under different ambient temperatures are obtained from the results measured at different substrate temperatures. The relationship between state power.

The conditions for the DC steady-state power aging of the measured GaN-based device include: using a microscopic infrared thermal imager to measure the junction temperature distribution of the device, and the ambient temperature is controlled at 70°C. Since the junction temperature reaches Tjm and continues to work, For devices with low voltage and low power consumption junction temperature distribution, the junction temperature distribution may become extremely uneven at high voltage and high power consumption, and obvious hot spots will appear, which may even lead to device failure, while the environment affects the junction temperature and thermal resistance of the device The influence is small, so when formulating the screening conditions, it should be carried out under the conditions of increasing the ambient temperature of the device, reducing the power dissipation and reducing the drain voltage of the added device, so the measured GaN-based device is under the condition of a junction temperature lower than 175°C In this case, the ambient temperature is 70°C, the bias conditions are drain voltage Vd=25V, and drain current Id=200mA.

The characteristic parameters of the measured GaN-based device include: drain current, threshold voltage, transconductance, Schottky turn-on voltage and reverse leakage current of the device. The threshold time for each characteristic parameter of the measured GaN-based device to be stable is determined from the time-varying curve of each characteristic parameter of the GaN-based device under test. The time when the characteristic parameters of the GaN-based device tend to be stable is determined as the threshold time for the parameters of the measured GaN-based device to stably enter the steady-state aging working area. When performing aging screening on multiple tested GaN-based devices, the multiple tested GaN-based devices are GaN-based devices of the same batch.

Example

The method for pre-screening the DC steady-state power aging of GaN-based devices provided in this embodiment is to perform micro-infrared measurement on AlGaN/GaN HEMTs to determine the DC steady-state power aging conditions of the devices, and perform device aging under these conditions. For DC steady-state power aging, the computer software is used to collect real-time changes in the characteristic parameters of the device over time, and obtain the change curve of each characteristic parameter of the device over time. Determine the time when the device characteristic parameters tend to be stable is the threshold time for the device to enter the stable period. Within this time range, pre-screen the device to eliminate the device whose parameters are difficult to stabilize. At the same time, the device has achieved the function of stabilizing parameters after aging. It is an effective and feasible method for performing DC steady-state power aging of GaN-based devices and realizing pre-screening, and specifically includes the following steps:

1. Package and test the device.

The single-tube bare-tube AlGaN/GaN HEMT device shown in Figure 2 is packaged in SG62A, and the packaged device is installed on a special jig, which is designed with an oscillation suppression circuit to eliminate the self-excited oscillation of the device for output The DC steady-state power of the device. Use a DC power supply to measure the DC steady-state power of the device, fix the drain terminal voltage, change the gate voltage of the device, obtain the corresponding leakage current, and measure the DC steady-state power of the device. The DC steady-state power is obtained by multiplying the current and voltage on the power supply.

2. Use micro-infrared to measure the junction temperature of the device to obtain the junction temperature distribution and peak junction temperature of the device, as shown in Figure 3, the steps are as follows:

(1) The micro-infrared tester controls the temperature of the fixture at 70°C through software;

(2) The device packaged in a single tube is mounted on a special fixture, which suppresses the self-excited oscillation of the device through an oscillation suppression circuit to output the DC steady-state power of the device.

(3) The microscopic infrared thermal imager detects the radiation energy density distribution of the chip and converts it into the temperature value of each point on the surface by computer software to accurately determine the peak temperature on the device.

3. As shown in Figure 4, mathematically fit the junction temperature measured by microscopic infrared to obtain the relationship between the peak junction temperature of the device and the DC steady-state power and the ambient temperature of the device, and determine the DC stability of the device. Conditions for state power aging:

(1) Calculate the DC steady-state power size of the device by the measured DC characteristics, where P=I _ds V _ds ;

(2) List the peak junction temperature corresponding to the DC steady state power. Listed by Table I.

(3) Obtain the mathematical relationship curve between the peak junction temperature and the corresponding DC steady-state power through the mathematical analysis software of Origin.

(4) From the results measured at different substrate temperatures, the relationship between the peak junction temperature of the device and the DC steady-state power at different ambient temperatures is obtained.

Table I Device DC power dissipation and peak junction temperature measurement results

4. Determine the conditions for peak junction temperature steady-state power aging of GaN-based HEMT devices.

Most of the steady-state working life experiments of GaN-based HEMT devices are carried out under the conditions of a certain case temperature and corresponding maximum rated power, according to T _j =P R _th (jc)+T _c (1)

From the screening point of view, there is no need to increase the rated power. The heat sink, air cooling and water cooling can be completely removed, and the power can be reduced. As long as the peak junction temperature is guaranteed, this is the basic principle of peak junction temperature screening. Under the condition of no additional heat dissipation, under the condition of rated case temperature, the case temperature of the device here is controlled at 70°C, and a certain DC steady-state power is applied to the GaN device to make the junction temperature reach Tjm and work continuously. For devices that consume junction temperature distribution, the junction temperature distribution may become extremely uneven at high voltage and high power consumption, and obvious hot spots will appear, and even cause device failure, and the environment has little influence on the junction temperature and thermal resistance of the device, so When formulating aging conditions, it should be carried out under the condition of increasing the ambient temperature of the device and reducing the power dissipation, especially the drain voltage of the device.

Therefore, the experimental conditions for steady-state aging of GaN-based devices are:

By controlling the ambient temperature around the fixture and controlling the shell temperature of the device, the temperature of the substrate where the device is located is 70°C;

The added drain voltage is 25V, and the drain current is 200mA;

Through the control software, the changes of the characteristic parameters Vd, Id, Vg and Ig of the device are collected in real time.

5. Determine the threshold time for the characteristic parameters of the device to become stable. After the threshold time, the characteristic parameters of the device tend to be stable, and it is considered that the device has entered a stable working life period. By monitoring the Vg and Ig curves of the device over time, the corresponding time when the characteristic parameters tend to be stable. After 390 hours of aging for device 1#10, the experiment was forced to be interrupted due to a power outage, and the experiment was continued. It was found that the characteristic parameters of 1#10 had stabilized. After the pre-aging, the characteristics of the device tend to be stable and enter the stable period of life. The following results verify the method.

6. For the same batch of devices with good consistency, perform steady-state power aging on the devices within the threshold time range, and remove devices whose characteristic parameters are difficult to stabilize within the threshold time, and at the same time after the steady-state power aging The device parameters are stabilized.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A method for pre-screening the DC steady-state power aging of GaN-based devices, characterized in that the method comprises: Carry out packaging test on the tested GaN-based device, and determine the DC steady-state power of the tested GaN-based device; Measure the junction temperature of the tested GaN-based device with a microscopic infrared thermal imager, and mathematically fit the measured junction temperature to obtain the relationship between the peak junction temperature of the tested GaN-based device and the DC steady-state power, and determine the measured Measure the conditions for DC steady-state power aging of GaN-based devices and the conditions of the ambient temperature during aging; Under the condition that the measured GaN-based device is subjected to DC steady-state power aging, the measured GaN-based device is subjected to DC steady-state power aging, and the change curve of each characteristic parameter of the measured GaN-based device with time is obtained; Determining the threshold time for each characteristic parameter of the device to stabilize from the time-varying curve of each characteristic parameter of the measured GaN-based device; and Perform aging screening on multiple GaN-based devices to be tested, and eliminate devices whose device characteristic parameters are difficult to stabilize within the threshold time, and realize pre-screening of DC steady-state power aging of GaN-based devices; Wherein, the junction temperature of the measured GaN-based device is measured with a microscopic infrared thermal imager, and the measured junction temperature is mathematically fitted to obtain the relationship between the peak junction temperature of the measured GaN-based device and the DC steady-state power relationship, to determine the conditions for the DC steady-state power aging of the GaN-based device under test and the ambient temperature conditions during aging, including: using a microscopic infrared thermal imager to measure the junction temperature of the GaN-based device under test, and obtain the GaN-based device under test The junction temperature distribution and peak junction temperature of the base device, and then use the Origin software to mathematically fit the measured junction temperature distribution and peak junction temperature to obtain the peak junction temperature of the device and the DC steady-state power and the relationship between the peak junction temperature and the device The relationship curve between the ambient temperatures, and then the relationship curve determines the conditions for the DC steady-state power aging of the GaN-based device under test. 2. The method for pre-screening the DC steady-state power aging of GaN-based devices according to claim 1, wherein the GaN-based device under test is packaged and tested to determine the DC steady-state power of the GaN-based device under test. state power, including: First, the GaN-based device under test is fixed on a fixture, which has a circuit for suppressing and eliminating the self-excited oscillation of the GaN-based device under test, and then uses a DC power supply to measure the DC characteristics of the GaN-based device under test. Measure the leakage voltage and leakage current of the GaN-based device under different gate voltages, and multiply the leakage voltage and leakage current to obtain the DC steady-state power of the GaN-based device under test. 3. The method for pre-screening the DC steady-state power aging of the GaN-based device according to claim 1, wherein the GaN-based device under test is packaged and tested to determine the DC steady-state power of the GaN-based device under test. The state power also includes: obtaining the corresponding temperature condition at this time. 4. The method for pre-screening the DC steady-state power aging of GaN-based devices according to claim 1, wherein the junction temperature of the measured GaN-based device is measured by a microscopic infrared thermal imager to obtain the obtained Measure the junction temperature distribution and peak junction temperature of GaN-based devices, including: The microscopic infrared thermal imager controls the temperature of the fixture at 70°C through software; The device packaged in a single tube is installed on the fixture, and the fixture suppresses the self-excited oscillation of the device through the suppression oscillation circuit, and outputs the DC steady-state power of the device; The microscopic infrared thermal imager detects the radiant energy density distribution of the chip and converts it into the temperature value of each point on the surface by computer software to determine the junction temperature distribution and peak junction temperature of the measured GaN-based device. 5. The method for pre-screening the DC steady-state power aging of GaN-based devices according to claim 1, wherein the condition for determining the measured GaN-based device to carry out DC steady-state power aging by the relationship curve, It is to determine the ambient temperature of the GaN-based device under test for DC steady-state power aging, that is, the temperature of the substrate, the drain voltage and the drain current. The temperature of the substrate is determined by the microscopic infrared method, and the drain voltage and drain current The current is obtained by measuring the DC characteristics of the GaN-based device under test by using a DC power supply. 6. The method for pre-screening the DC steady-state power aging of GaN-based devices according to claim 1, wherein the condition for determining the measured GaN-based device to carry out DC steady-state power aging by the relationship curve, include: Calculate the DC power of the GaN-based device under test from the measured leakage voltage and leakage current of the GaN-based device under different gate voltages; Through the mathematical analysis software of Origin, the mathematical relationship curve between the peak junction temperature and the corresponding DC steady-state power is obtained; From the results measured at different substrate temperatures, the relationship between the peak junction temperature of the device and the DC steady-state power at different ambient temperatures is obtained. 7. The method for pre-screening the DC steady-state power aging of GaN-based devices according to claim 6, wherein the conditions for performing DC steady-state power aging of the GaN-based device under test include: The measured GaN-based device is under the condition that the junction temperature is lower than 175°C, the ambient temperature is 70°C, the bias conditions are drain voltage Vd=25V, and drain current Id=200mA. 8. The method for pre-screening the DC steady-state power aging of GaN-based devices according to claim 1, wherein the characteristic parameters of the measured GaN-based devices include: drain current and threshold voltage of the device , transconductance, Schottky turn-on voltage and reverse leakage current. 9. The method for pre-screening the DC steady-state power aging of GaN-based devices according to claim 1, wherein the characteristics of the device are determined by the time-varying curve of each characteristic parameter of the GaN-based device under test. The threshold time for the parameter to stabilize is to determine the time when the characteristic parameters of the measured GaN-based device become stable by the change curve of each characteristic parameter of the measured GaN-based device with time, and to determine the time for the stabilized time to be measured The threshold time for GaN-based device parameters to stabilize into the steady-state aging working region. 10. The method for pre-screening the DC steady-state power aging of GaN-based devices according to claim 1, wherein, when performing aging screening on a plurality of GaN-based devices under test, the plurality of GaN-based devices under test The base devices are GaN-based devices from the same batch.