A rapid high temperature test method for power semiconductors

Abstract

The application belongs to the technical field of integrated circuit testing, and discloses a rapid high-temperature testing method for a power semiconductor, which comprises the following steps: drawing a voltage drop-internal junction temperature relationship curve of a diode inside the device; drawing an internal junction temperature-surface shell temperature relationship curve of the device; establishing a relationship model among the voltage drop, the internal junction temperature and the surface shell temperature; applying a predetermined heating voltage and a testing current to a testing object, monitoring the voltage drop of the internal diode in real time, and calculating the corresponding internal junction temperature and surface shell temperature according to the relationship model; and when the internal junction temperature and the surface shell temperature reach target values, immediately stopping the application of the heating voltage and the current, and simultaneously carrying out electrical parameter testing on the testing object. Through the application, the accuracy and efficiency of the whole testing process can be significantly improved, the testing conditions are closer to the actual working state, the testing cost is reduced, and more reliable data support can be provided for the design and application of the power semiconductor.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of integrated circuit testing, and more particularly, to a rapid high-temperature testing method for power semiconductors. BACKGROUND

[0002] At present, the testing and experiments of power semiconductors usually need to be high-temperature tested to verify their performance under maximum load and maximum allowable operating temperature. In the prior art, the common testing method is to place the power semiconductor in a high-temperature oven, heat the oven to the set temperature, and in order to ensure that the internal junction temperature reaches the set value, it needs to be stabilized in the oven for a period of time, and then taken out for rapid testing.

[0003] However, further studies have shown that the above prior art still has the following defects or deficiencies: due to the slow heating speed of the oven and the need for a long stabilization time, which is usually more than half an hour in the industry, which leads to low testing efficiency; in addition, the temperature gradient often exists in the heating process of the oven, which leads to the deviation of the subsequent high-temperature test structure from the actual result, etc.

[0004] In order to realize the rapid high-temperature testing of semiconductors, CN201410134465.6 proposes a method of realizing device short circuit by PWM control of the gate of the device to be tested to realize rapid heating, which estimates the temperature of the semiconductor after heating by the external power supply by deducing the temperature difference of the device from the heat generated by the semiconductor per unit area. However, the formula in this method is only a theoretical calculation of the temperature rise, and it does not take into account the differences in the thermal resistance of the specific chip and the testing environment such as whether there is air conditioning wind, etc. At the same time, since the device is also a heat dissipation process during heating, the longer the time of PWM heating, the more heat dissipation. This method uses the theoretical calculation method to obtain the PWM control waveform and time, and does not know whether the temperature of the device after actual heating is sufficient or exceeds the temperature bearing range of the device, etc. Therefore, this method cannot accurately solve the problem of rapid high-speed testing of semiconductors.

[0005] In order to accurately obtain the current junction temperature and case temperature of the semiconductor, the temperature sensor is usually tightly attached to the surface of the semiconductor device for measurement, and there is also a method of testing the device junction temperature through the internal diode, for example, US2019 / 0178726A1 declares a method of placing a diode inside a power device for estimating the internal temperature of the device. But this method is only used for internal temperature detection in chip design and cannot be applied to high-temperature heating of semiconductors, and when the device to be tested does not have an internal diode, it cannot estimate the temperature.

[0006] Accordingly, it is necessary in this field to further research and improve high-temperature testing solutions for power semiconductors in order to better meet the testing requirements of high precision and high efficiency. Summary of the Invention

[0007] In response to the above-mentioned defects or needs of the prior art, the purpose of the present invention is to provide a rapid high-temperature testing method and system for power semiconductors, in which the entire testing process method is redesigned and targeted improvements are made to its key steps by closely combining the high-temperature testing characteristics and specific needs of various types of power semiconductors. Accordingly, the accuracy and efficiency of the entire testing process can be significantly improved, making the test conditions closer to the actual working conditions, while reducing the testing costs, and providing more reliable data support for the design and application of power semiconductors.

[0008] To achieve the above object, according to one aspect of the present invention, a method for rapid high-temperature testing of power semiconductors is provided, characterized in that the method comprises the following steps:

[0009] S1. Place a power semiconductor device sample in an incubator at a set temperature. After the internal and external temperatures of the device sample are balanced, measure the voltage drop and internal junction temperature of the internal diode of the device sample multiple times, and draw a first relationship curve between the corresponding diode voltage drop and internal junction temperature, i.e., a voltage drop-internal junction temperature relationship curve.

[0010] S2. Applying current to a power semiconductor device sample at room temperature to cause it to heat up, measuring a voltage drop across an internal diode of the device sample, and deriving a corresponding internal junction temperature based on a voltage drop-internal junction temperature relationship curve; then, controlling the magnitude of the applied current so that the internal junction temperature of the device sample remains constant at the internal junction temperature, and after the internal and external temperatures of the device sample have reached equilibrium, measuring the surface case temperature of the device sample at this time;

[0011] The applied current is varied multiple times, and the voltage drop of the internal diode of the device sample is measured accordingly, and the corresponding internal junction temperature is derived from the voltage drop-internal junction temperature relationship curve; then, the internal junction temperature of the device sample is maintained constant at the internal junction temperature by controlling the magnitude of the applied current each time, and after the internal and external temperatures of the device sample are balanced, the surface case temperature of the device sample is measured each time;

[0012] Based on the internal junction temperature and surface case temperature data obtained above, a second relationship curve between the internal junction temperature and the surface case temperature of the relevant device under normal temperature conditions, namely, an internal junction temperature-surface case temperature relationship curve, is drawn;

[0013] S3. Based on the above voltage drop-internal junction temperature relationship curve and the internal junction temperature-surface shell temperature relationship curve, a relationship model among the voltage drop of the diode, the internal junction temperature of the device, and the surface shell temperature, i.e., a voltage drop-internal junction temperature-surface shell temperature relationship model, is established;

[0014] S4. Place the power semiconductor device to be tested on a semiconductor test system fixture and connect the required test instruments.

[0015] S5. Apply a predetermined heating voltage and test current to achieve rapid internal temperature rise of the test object, monitor the actual voltage drop of the internal diode in real time, and then directly calculate the corresponding internal junction temperature and surface case temperature data based on the above voltage drop-internal junction temperature-surface case temperature relationship model;

[0016] Changing the heating voltage and the test current, and detecting the actual voltage drop of the internal diode in the above manner until the calculated internal junction temperature and surface case temperature data reach the set target values;

[0017] S6. When the calculated internal junction temperature and surface shell temperature data reach the set target value, immediately stop applying the heating voltage and current, and at the same time, carry out electrical parameter testing on the test object according to the test items;

[0018] S7. When the test is completed, the next test object is replaced and the process goes to S4 to restart the corresponding rapid heating and electrical parameter test process.

[0019] Further preferably, in step S1, a semiconductor thermal resistance testing method is preferably selected to directly test the voltage drop and internal junction temperature data of the internal diode of the device sample through a thermal resistance testing device, and draw a corresponding voltage drop-internal junction temperature relationship curve.

[0020] Further preferably, in the above voltage drop-internal junction temperature-surface case temperature relationship model, the internal junction temperature curve and the surface case temperature curve decrease approximately linearly with increasing temperature.

[0021] Further preferably, as the temperature increases, the diode voltage drop rate corresponding to the surface shell temperature curve is greater than the diode voltage drop rate corresponding to the internal junction temperature curve.

[0022] Further preferably, in steps S4 and S5, the test object is preferably connected to a semiconductor automatic test system through a switch K1, and the diode voltage drop measuring instrument is connected to the pin corresponding to the internal diode of the test object through a switch K2; then, the power supply and the drive circuit are respectively connected to the load pin and the drive pin of the test object through a switch K3, so that the drive circuit can drive the drive pin of the test object to be in a conductive state, and the programmable power supply makes the test object heat up by applying current; the temperature calculation and control unit reads the voltage drop data measured by the diode voltage drop measuring instrument in real time, and calculates the real-time data of the internal junction temperature and external shell temperature of the test object based on the above-mentioned voltage drop-internal junction temperature-surface shell temperature relationship model, thereby controlling the output voltage and current of the programmable power supply in real time so as to control the internal shell temperature and external shell temperature of the device under test to reach and not exceed the preset target value.

[0023] Further preferably, in step S6, it is also preferably included to immediately disconnect switches K2 and K3 after the test object reaches the target value, and simultaneously connect K1 and perform a rapid test on the electrical parameters of the device through a semiconductor automatic test system.

[0024] Further preferably, when the electronic device has no internal diode, the temperature can be measured by directly installing a contact or non-contact temperature sensor on the outside.

[0025] According to another aspect of the present invention, a corresponding rapid high-temperature test system is also provided, which cooperates with a semiconductor automatic test system (ATE) to achieve high-temperature heating of semiconductors and semiconductor parameter testing at a set temperature. The system is characterized in that it includes a switch connected to the device to be tested, a diode voltage drop test instrument, a programmable power supply, a device drive circuit, a temperature calculation and control (or computer), and a semiconductor automatic test system (ATE), wherein:

[0026] The temperature calculation and control component controls the programmable power supply, the drive circuit, and the diode voltage drop measuring instrument. The semiconductor automatic test system (ATE) communicates with the temperature calculation and control component to interactively perform heating and testing. Specifically, the ATE first disconnects K1 and communicates with the temperature calculation and control component, causing the component to control switch K3 connected to the device under test. The drive circuit then controls the internal switch of the test object, allowing the programmable power supply to output current through the device under test for heating. After a certain heating period, switch K3 is disconnected and switch K2 is closed, connecting the diode voltage drop measuring instrument to the internal temperature of the test object. If the temperature reaches the set temperature, switch K2 is closed and the semiconductor test system is notified to close switch K1 to begin electrical performance parameter testing of the semiconductor device. If the temperature does not reach the set temperature, switch K2 is disconnected and switch K3 is closed to continue heating the device.

[0027] Further preferably, the temperature is monitored in real time by installing an infrared device or a contact test device directly on the device to be tested; in this way, the switching times of the switches K2 and K3 are reduced, further improving the efficiency.

[0028] In general, the above technical solutions conceived by the present invention have the following technical advantages compared with the existing technology:

[0029] 1. This invention closely combines the high-temperature test characteristics and specific requirements of various power semiconductors. By directly applying the test voltage and current to the actual test object, it can achieve rapid internal temperature rise, greatly shortening the temperature rise time. At the same time, since the temperature chamber heating and stabilization time are eliminated, the test efficiency is significantly improved and the overall test time is reduced.

[0030] 2. By real-time monitoring and calculating the relationship between the internal diode and temperature of the power semiconductor, the present invention can more accurately control and predict the internal junction temperature and external case temperature, thereby improving test accuracy. For devices without diodes, an additional temperature sensor can be installed to monitor the device case temperature in real time. When the device temperature reaches the set temperature, heating is stopped and the device electrical parameters are immediately tested. In addition, the power semiconductor is always fixed to the test fixture, eliminating the need for removal and placement operations, ensuring the continuity and stability of the test.

[0031] 3. Compared with the external heating method in the prior art, the present invention adopts rapid internal heating, which can effectively reduce the temperature gradient and make the test conditions closer to the actual working state;

[0032] 4. The rapid high-temperature testing method of the present invention reduces equipment requirements, can reduce testing costs, and improve economic benefits. At the same time, since the temperature control during the entire testing process is more precise, the obtained data is more reliable, thus providing solid data support for the performance evaluation of various power semiconductors. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a main process flow chart of the rapid high temperature testing method according to the present invention;

[0034] Figure 2 is a schematic diagram (diode voltage drop-junction temperature-case temperature curve diagram) for exemplarily illustrating a voltage drop-internal junction temperature-surface case temperature relationship model of a rapid high-temperature test system of the present invention;

[0035] Figure 3 is a diagram of the deployment of the test system and the heating system when there is an internal diode according to the present invention;

[0036] Figure 4 FIG. 4 is a diagram showing the deployment of a test system and a heating system without an internal diode according to the present invention. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0038] It should be understood that expressions such as "include" and "may include" used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "include" and / or "have" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0039] It should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0041] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0042] The present invention will be explained in detail below through a specific example.

[0043] Example 1

[0044] Step 1: Place a power semiconductor device sample in an incubator at a set temperature. After the internal and external temperatures of the device sample are balanced, measure the voltage drop and internal junction temperature data of the internal diode of the device sample multiple times, and draw a first relationship curve between the corresponding diode voltage drop and internal junction temperature, namely, the voltage drop-internal junction temperature relationship curve.

[0045] More specifically, in this step one, a semiconductor thermal resistance test method is preferably selected to directly test the voltage drop and internal junction temperature data of the internal diode of the device sample through a thermal resistance test device, and draw a corresponding voltage drop-internal junction temperature relationship curve.

[0046] Step 2: Apply current to a power semiconductor device sample at room temperature to generate heat, measure the voltage drop Δp1 of the internal diode of the device sample, and derive the corresponding internal junction temperature tj1 based on the voltage drop-internal junction temperature relationship curve; then, control the magnitude of the applied current so that the internal junction temperature of the device sample remains constant at the internal junction temperature tj1. After the internal and external temperatures of the device sample are balanced, measure the surface case temperature ts1 of the device sample at this time;

[0047] The applied current is varied, and the voltage drop Δp2 of the internal diode of the device sample is measured again. The corresponding internal junction temperature tj2 is derived based on the voltage drop-internal junction temperature relationship curve. Next, the applied current is controlled so that the internal junction temperature of the device sample remains constant at the internal junction temperature tj2. After the internal and external temperatures of the device sample equilibrate, the surface case temperature ts2 of the device sample is measured.

[0048] …

[0049] Repeat the above process multiple times and draw a second relationship curve between the internal junction temperature and the surface case temperature of the relevant device under normal temperature conditions, that is, the internal junction temperature-surface case temperature relationship curve;

[0050] Step 3: Combine the above voltage drop-internal junction temperature relationship curve and the internal junction temperature-surface case temperature relationship curve to establish a relationship model among the voltage drop of the diode, the internal junction temperature of the device, and the surface case temperature, i.e., the voltage drop-internal junction temperature-surface case temperature relationship model or relationship curve.

[0051] Step 4: Place the power semiconductor device to be tested on a semiconductor test system fixture and connect it to the required test instruments.

[0052] More specifically, the power semiconductor device to be tested can be placed on a semiconductor test system fixture and connected to the test instruments required by the temperature prediction model. A 6.5-digit digital multimeter is used as the diode voltage drop test instrument. A programmable power supply selects a power supply with CC mode based on the device's power level. A computer is used as the temperature calculation domain control module. The driver circuit uses the device's dedicated driver circuit to set the turn-on and turn-off levels for the device under test. The computer communicates with the programmable power supply, digital multimeter, and driver circuit via a serial port and with the semiconductor automatic test system (ATE) via Ethernet. For devices under test without internal diodes, a temperature test sensor is installed.

[0053] Step 5. Apply a predetermined heating voltage and test current to achieve rapid internal temperature rise of the test object, and monitor the actual voltage drop of its internal diode in real time. Then, directly calculate the corresponding internal junction temperature and surface case temperature data based on the above-mentioned voltage drop-internal junction temperature-surface case temperature relationship model; change the heating voltage and test current, and detect the actual voltage drop of the internal diode in the above-mentioned manner until the calculated internal junction temperature and surface case temperature data reach the set target values.

[0054] More specifically, for example, switch K1 can be disconnected and switch K3 opened, driving the DUT into the on state. A programmable power supply applies a heating current to achieve rapid internal temperature increase. After a short heating period, K3 is disconnected and K2 is connected to test the diode voltage drop using the diode test function of a digital multimeter, thereby estimating the device's internal junction temperature and external case temperature. For devices without internal diodes, the temperature sensor is read directly. If the temperature reaches the set temperature, K2 is closed and the semiconductor test system is notified to close K1 to begin electrical performance parameter testing of the semiconductor device. If the temperature does not reach the set temperature, K2 is disconnected and K3 is closed to continue heating the device.

[0055] Step 6. When the calculated internal junction temperature and surface shell temperature data reach the set target values, immediately stop applying the heating voltage and current, and at the same time, perform electrical parameter testing on the test object according to the test items.

[0056] More specifically, in this step, when the monitored junction temperature reaches the preset safe operating temperature, the power supply output is immediately adjusted to stop further temperature rise. Next, the device is connected to a semiconductor automated test system for required electrical characteristic tests, such as on-state voltage drop and switching speed. All key test data, including voltage, current, temperature, and time, are recorded during the test.

[0057] Step 7: When the test is completed, replace the next test object and go to step 4 to restart the corresponding rapid heating and electrical parameter test process.

[0058] Through the above concept, on the one hand, since there is a linear relationship between the voltage, current and temperature of the power semiconductor. Since the normal temperature calibration has been passed before testing, the junction temperature inside the power semiconductor calculated by the voltage and current passing through the load end can be accurately predicted. When the junction temperature reaches the set temperature, the application of high voltage and high current can be stopped, and the test can be quickly carried out. During the whole test process, the power semiconductor is always fixed on the test fixture, without taking out and placing, ensuring the continuity and accuracy of the test; on the other hand, compared with the traditional external heat conduction heating method, the method of the application realizes rapid heating by internally applying voltage and current, ensuring the accuracy of the junction temperature inside the power semiconductor. In addition, since the power semiconductor is always in the test fixture during the test process, the test speed is fast, the internal temperature change is small, and it is closer to the set junction temperature.

[0059] In addition, after the above steps, the electrical characteristic test results can also be analyzed to evaluate the performance of the test object at high temperature. For example, data analysis software can be used to analyze the test results, and automatically evaluate the performance of the power semiconductor at high temperature.

[0060] In summary, the rapid high-temperature test method and system according to the application provide a more efficient, fast and test parameter closer to the actual parameter under the set temperature test scheme. Among them, by directly applying high voltage and high current, not only the test efficiency is improved, but also since the temperature measurement is located inside the power semiconductor, the accuracy of the test result is ensured.

[0061] Those skilled in the art will readily understand that the above description is only a preferred embodiment of the application and is not intended to limit the application. Any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A rapid high-temperature testing method for power semiconductors, characterized in that: The method comprises the following steps: S1. Place a power semiconductor device sample in an incubator at a set temperature. After the internal and external temperatures of the device sample are balanced, measure the voltage drop and internal junction temperature of the internal diode of the device sample multiple times, and draw a first relationship curve between the corresponding diode voltage drop and internal junction temperature, i.e., a voltage drop-internal junction temperature relationship curve. S2. Applying current to a power semiconductor device sample at room temperature to cause it to heat up, measuring a voltage drop across an internal diode of the device sample, and deriving a corresponding internal junction temperature based on a voltage drop-internal junction temperature relationship curve; then, controlling the magnitude of the applied current so that the internal junction temperature of the device sample remains constant at the internal junction temperature, and after the internal and external temperatures of the device sample have reached equilibrium, measuring the surface case temperature of the device sample at this time; The applied current is varied multiple times, and the voltage drop of the internal diode of the device sample is measured accordingly, and the corresponding internal junction temperature is derived from the voltage drop-internal junction temperature relationship curve; then, the internal junction temperature of the device sample is maintained constant at the internal junction temperature by controlling the magnitude of the applied current each time, and after the internal and external temperatures of the device sample are balanced, the surface case temperature of the device sample is measured each time; Based on the internal junction temperature and surface case temperature data obtained above, a second relationship curve between the internal junction temperature and the surface case temperature of the relevant device under normal temperature conditions, namely, an internal junction temperature-surface case temperature relationship curve, is drawn; S3. Based on the above voltage drop-internal junction temperature relationship curve and the internal junction temperature-surface shell temperature relationship curve, a relationship model among the voltage drop of the diode, the internal junction temperature of the device, and the surface shell temperature, i.e., a voltage drop-internal junction temperature-surface shell temperature relationship model, is established; S4. Place the power semiconductor device to be tested on a semiconductor test system fixture and connect the required test instruments. S5. Apply a predetermined heating voltage and test current to achieve rapid internal temperature rise of the test object, monitor the actual voltage drop of the internal diode in real time, and then directly calculate the corresponding internal junction temperature and surface case temperature data based on the above voltage drop-internal junction temperature-surface case temperature relationship model; Changing the heating voltage and the test current, and detecting the actual voltage drop of the internal diode in the above manner until the calculated internal junction temperature and surface case temperature data reach the set target values; S6. When the calculated internal junction temperature and surface shell temperature data reach the set target value, immediately stop applying the heating voltage and current, and at the same time, carry out electrical parameter testing on the test object according to the test items; S7. When the test is completed, the next test object is replaced and the process goes to S4 to restart the corresponding rapid heating and electrical parameter test process.

2. The rapid high temperature testing method according to claim 1, wherein: In step S1, a semiconductor thermal resistance test method is selected to directly test the voltage drop and internal junction temperature data of the internal diode of the device sample through a thermal resistance test device, and a corresponding voltage drop-internal junction temperature relationship curve is drawn.

3. The rapid high temperature testing method according to claim 2, wherein: In the above voltage drop-internal junction temperature-surface case temperature relationship model, the internal junction temperature curve and the surface case temperature curve generally decrease linearly with increasing temperature.

4. The rapid high temperature testing method according to claim 3, wherein: As the temperature increases, the diode voltage drop corresponding to the surface shell temperature curve decreases faster than the diode voltage drop corresponding to the internal junction temperature curve.

5. The rapid high temperature testing method according to claim 1, wherein: In steps S4 and S5, the test object is connected to the semiconductor automatic test system through switch K1, and the diode voltage drop measuring instrument is connected to the pin corresponding to the internal diode of the test object through switch K2; Next, the power supply and the drive circuit are connected to the load pin and the drive pin of the test object respectively through the switch K3, so that the drive circuit can drive the drive pin of the test object to be in a conductive state, and the programmable power supply applies current to heat the test object; The temperature calculation and control unit reads the voltage drop data measured by the diode voltage drop measuring instrument in real time, and calculates the real-time data of the internal junction temperature and external case temperature of the test object based on the above-mentioned voltage drop-internal junction temperature-surface case temperature relationship model, thereby controlling the output voltage and current of the programmable power supply in real time to control the internal case temperature and external case temperature of the device under test to reach and not exceed the preset target value.

6. The rapid high temperature testing method according to claim 5, characterized in that: In step S6 , it is also included that after the test object reaches the target value, switches K2 and K3 are immediately disconnected, K1 is connected at the same time, and the electrical parameters of the device are quickly tested through the semiconductor automatic test system.

7. The rapid high temperature testing method according to claim 1, wherein: When an electronic device does not have an internal diode, temperature measurement is performed by directly mounting a contact or non-contact temperature sensor externally.

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