GaN power device structure and junction temperature testing device

Abstract

The invention discloses a GaN power device structure, and a junction temperature testing device comprises an N-type SiC substrate, the upper end of the N-type SiC substrate is provided with a buffer layer, metal is deposited at the upper end of the buffer layer to form a drain metal layer, the upper end of the drain metal layer is provided with a conduction layer formed by a highly doped N-type GaN layer, and the upper end of the conduction layer is provided with an N-type GaN layer. The upper end of the conduction layer is provided with a drift region formed by a lightly doped N-type GaN layer, the drift region is internally provided with alternately arranged P-type GaN layers, the lower ends of the P-type GaN layers are in contact with the conduction layer, the upper end of the drift region is provided with a blocking layer formed by the P-type GaN layers, the upper end of the blocking layer is provided with a source electrode contact layer formed by a highly doped N-type GaN layer, and the upper end of the source electrode contact layer is provided with an N-type GaN layer. The upper end of the source electrode contact layer is etched downwards to form a groove, an insulating layer is arranged in the groove, the upper end of the insulating layer is deposited to form a grid electrode, and metal is deposited at the upper end of the source electrode contact layer to form a source electrode. According to the invention, the breakdown voltage can be effectively improved, the device works stably under higher voltage, the temperature rise during working of the device is reduced, and the service life of the device is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of microelectronic technology, and in particular to a GaN power device structure and a junction temperature testing device. Background Art

[0002] In recent years, with the development of wide bandgap semiconductor materials, GaN (gallium nitride) has become one of the important candidate materials for high-performance power electronic devices due to its unique physical and electronic properties. GaN power devices, especially vertical GaN power devices, have attracted much attention due to their significant advantages in high voltage, high current and high frequency applications. Although traditional planar GaN power devices have made great progress, they still face some challenges in high voltage and high current applications, such as high on-resistance, limited breakdown voltage and poor thermal management capabilities.

[0003] To solve these problems, researchers have developed a new type of vertical GaN power device that uses a superjunction composite structure design. This structure effectively optimizes the electric field distribution, reduces the on-resistance, and significantly improves the breakdown voltage by alternately arranging p-type GaN layers and n-type GaN layers in the drift region. In addition, the device also uses high-performance substrate materials, such as n-type SiC, and high-quality buffer layers to further improve the performance and reliability of the device.

[0004] Although the superjunction composite structure has been able to significantly increase the breakdown voltage and reduce the on-resistance, how to further optimize the electric field distribution by adjusting the thickness and doping concentration of the p-type and n-type layers to increase the breakdown voltage while reducing the on-resistance is still a direction worth exploring. Although the design of the vertical structure helps to improve thermal management, in high power density applications, how to design a more effective heat dissipation system to ensure the long-term stability and reliability of the device in high power density applications is still an important technical challenge. Summary of the invention

[0005] The purpose of the present invention is to provide a GaN power device structure and a junction temperature testing device, which can effectively improve the breakdown voltage, stably operate at a higher voltage, help reduce the temperature rise of the device during operation, and extend the life of the device.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] A GaN power device structure comprises an N-type SiC substrate, wherein a buffer layer is arranged at the upper end of the N-type SiC substrate, a conduction layer formed of a highly doped N-type GaN layer is arranged at the upper end of the buffer layer, a drift region formed of a lightly doped N-type GaN layer is arranged at the upper end of the conduction layer, alternately arranged P-type GaN layers are arranged in the drift region, the lower end of each P-type GaN layer is in contact with the conduction layer, the P-type GaN layers and the N-type GaN layers in the drift region are alternately arranged to form a superjunction composite structure, a blocking layer formed of a P-type GaN layer is arranged at the upper end of the drift region, a source contact layer formed of a highly doped N-type GaN layer is arranged at the upper end of the blocking layer, a groove extending to the drift region is etched downward from the upper end of the source contact layer, an insulating layer is arranged in the groove, the upper end of the insulating layer is deposited to form a gate, a metal is deposited at the upper end of the source contact layer to form a source, and a metal is deposited at the lower end of the N-type SiC substrate to form a drain metal layer.

[0008] Further preferably, the buffer layer is an N-type doped AlN layer.

[0009] Further preferably, the insulating layer uses SiO2 as the metal material.

[0010] Further preferably, the gate uses Ti as the metal material.

[0011] Further preferably, the source electrode uses Al as the metal material.

[0012] Further preferably, the drain metal layer uses Cu as the metal material.

[0013] The present invention also provides a junction temperature testing device for performing a junction temperature test on the above-mentioned GaN power device structure, comprising a control module, a voltage generating module, a current generating module and a voltage measuring module, wherein the voltage generating module is respectively connected to the gate and the control module, the current generating module is connected to both ends of the source and drain metal layers and is also connected to the control module, the voltage measuring module is connected to both ends of the source and drain metal layers and is also connected to the control module, the control module is used to output corresponding control instructions to the voltage generating module, the current generating module and the voltage measuring module, and determine the junction temperature of the GaN power device according to the measured voltages across the source and drain metal layers.

[0014] In summary, the present invention has the following beneficial effects:

[0015] First, improve the breakdown voltage: By alternately arranging p-type GaN layers and n-type GaN layers in the drift region to form a superjunction composite structure, the electric field distribution can be optimized, thereby significantly improving the breakdown voltage of the device. This means that the device can work stably at a higher voltage and is suitable for high-voltage power conversion applications.

[0016] Second, reduce on-resistance: The superjunction composite structure can reduce the resistance of the drift region, thereby reducing the on-resistance of the device in the on state. Lower on-resistance means lower energy loss and improved overall energy efficiency.

[0017] Third, improve thermal management: The vertical structure design allows the current to flow from the top to the bottom of the device, which helps improve thermal management. Using substrate materials with good thermal conductivity, such as n-type SiC, can effectively improve heat dissipation efficiency, thereby reducing the temperature rise of the device during operation and extending the device life.

[0018] Fourth, improve reliability: Using high-quality buffer layers, such as AlN layers, can reduce interface defects and improve the overall quality of the material. This helps reduce device failures during long-term operation, thereby improving device reliability.

[0019] Fifth, support high-frequency operation: The inherent high electron mobility of GaN materials enables vertical GaN power devices to support high-frequency operation, which is very important for modern power electronic systems because it can reduce the size and weight of external passive components and improve the overall performance of the system.

[0020] Sixth, suitable for high power density applications: These characteristics of vertical GaN power devices make them very suitable for high power density application scenarios such as electric vehicle charging systems, solar inverters, uninterruptible power supplies (UPS) and data center power management systems.

[0021] Seventh, since the current injected into the source and drain metal layers of the junction temperature testing device of the present invention is a pulse current, the current value can be set to a larger value. On the one hand, it solves the problems of too low test voltage, poor resistance to electrical noise interference, and low overall test accuracy caused by small current injection. On the other hand, since the pulse current conduction time is short, it avoids the problem of introducing too much additional heat due to large current injection, thereby improving the accuracy of the junction temperature test. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic structural diagram of the GaN power device in Example 1;

[0023] Figure 2 It is a connection diagram of Example 2.

[0024] In the figure: 1. N-type SiC substrate; 2. buffer layer; 3. conduction layer; 4. drift region; 5. P-type GaN layer; 6. blocking layer; 7. source contact layer; 8. insulating layer; 9. gate; 10. source; 11. drain metal layer; 12. control module; 13. voltage generation module; 14. current generation module; 15. voltage measurement module. DETAILED DESCRIPTION

[0025] The following is a further detailed description of a GaN power device structure and a junction temperature test device proposed in the present invention in combination with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will become clearer. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. The same or similar figure numbers in the accompanying drawings represent the same or similar components.

[0026] Example 1, reference Figure 1 A GaN power device structure comprises an N-type SiC substrate 1, a buffer layer 2 formed of N-type doped AlN is arranged on the upper end of the N-type SiC substrate 1, a conduction layer 3 formed of a highly doped N-type GaN layer is arranged on the upper end of the buffer layer 2, a drift region 4 formed of a lightly doped N-type GaN layer is arranged on the upper end of the conduction layer 3, and alternately arranged P-type GaN layers 5 are arranged in the drift region 4, the lower end of each P-type GaN layer 5 is in contact with the conduction layer 3, and the P-type GaN layer 5 and the N-type GaN layer of the drift region 4 are alternately arranged to form Super junction composite structure, a blocking layer 6 formed of a P-type GaN layer is arranged at the upper end of the drift region 4, a source contact layer 7 formed of a highly doped N-type GaN layer is arranged at the upper end of the blocking layer 6, a groove extending to the drift region 4 is etched downward from the upper end of the source contact layer 7, an insulating layer 8 formed by SiO2 deposition is arranged in the groove, a gate 9 is formed by metal Ti deposition at the upper end of the insulating layer 8, a source 10 is formed by metal Al deposition at the upper end of the source contact layer 7, and a drain metal layer 11 is formed by metal Gu deposition at the lower end of the N-type SiC substrate 1.

[0027] Process:

[0028] 1. Substrate preparation: Use N-type SiC substrate as the base to provide mechanical support and good thermal management.

[0029] 2. Buffer layer growth: Grow an N-type doped AlN buffer layer on the SiC substrate to reduce the lattice mismatch between SiC and GaN.

[0030] 3. Growth of N-type GaN layer: Grow an N-type GaN layer on the AlN buffer layer as a conducting layer.

[0031] 4. Drift region growth: A lightly doped N-type GaN layer is grown on the N-type GaN layer as a drift region responsible for withstanding high voltage.

[0032] 5. Superjunction composite structure growth: Alternating P-type GaN layers and N-type GaN layers are grown in the drift region to form a superjunction composite structure, which is used to optimize the electric field distribution and increase the breakdown voltage.

[0033] 6. Blocking layer growth: A P-type GaN layer is grown above the drift region as a blocking layer to prevent current flow in the off state.

[0034] 7. Growth of N-type GaN layer: A highly doped N-type GaN layer is grown on top of the blocking layer as a source contact layer.

[0035] 8. Groove formation: A groove is etched downward in the middle of the source contact layer. This groove will penetrate the blocking layer to the drift region.

[0036] 9. Insulating layer deposition: Deposit an insulating layer of metal SiO2 inside the trench.

[0037] 10. Gate material deposition: Deposit gate material with metal Ti above the insulating layer.

[0038] 11. Source metal contact deposition: Deposit metal contact material Al on top of the N-type GaN layer.

[0039] 12. Drain metal layer metal contact deposition: deposit metal contact material Cu on the back of SiC substrate.

[0040] 13. Packaging: Perform necessary packaging steps to protect the device and ensure good thermal management.

[0041] Working principle details:

[0042] Switch Operation:

[0043] Off state: When the gate voltage is lower than the threshold voltage, the charge in the drift region under the gate will be depleted to form a depletion region, which prevents current from flowing from the source to the drain metal layer.

[0044] On state: When the gate voltage is higher than the threshold voltage, charges are accumulated in the drift region under the gate, forming a conductive channel that allows current to flow from the source to the drain metal layer.

[0045] Electric field optimization:

[0046] Super junction composite structure: By alternately arranging P-type GaN layers and N-type GaN layers in the drift region, the electric field distribution can be optimized, making the electric field more uniform in the drift region, thereby increasing the breakdown voltage.

[0047] Blocking layer: The addition of the P-type GaN layer helps to prevent the flow of current in the off state, further improving the voltage resistance of the device.

[0048] Thermal Management:

[0049] Substrate: N-type SiC substrate has good thermal conductivity, which helps to conduct the heat generated by the device from top to bottom.

[0050] Structural design: The vertical structure allows current to flow from top to bottom, which helps dissipate heat.

[0051] Example 2, reference Figure 2 A junction temperature testing device is provided, which is used to perform a junction temperature test on a GaN power device structure of Example 1, and includes a control module 12, a voltage generating module 13, a current generating module 14 and a voltage measuring module 15; the voltage generating module 13 is connected to the gate 9 and the control module 12 respectively; the current generating module 14 is connected to both ends of the source 10 and the drain metal layer 11, and is also connected to the control module 12; the voltage measuring module 15 is connected to both ends of the source 10 and the drain metal layer 11, and is also connected to the control module 12; the control module 12 is used to output corresponding control instructions to the voltage generating module 13, the current generating module 14 and the voltage measuring module 15, and determine the junction temperature of the GaN power device according to the measured voltages across the source 10 and the drain metal layer 11.

[0052] 1. Control module

[0053] Function: As the core of the entire system, the control module is responsible for receiving external instructions or generating control instructions according to preset logic, and sending these instructions to the voltage generation module, current generation module and voltage measurement module.

[0054] Operation: According to the test requirements or algorithms, the control module can adjust the waveform, amplitude, frequency and other parameters of the voltage and current, and trigger the generation of voltage and current, while collecting data from the voltage measurement module for subsequent analysis.

[0055] 2. Voltage generation module

[0056] Function: According to the instructions of the control module, generate and output a specific voltage to the gate of the GaN power device to control the conduction state of the device.

[0057] Operation: At the beginning of the test, the voltage generation module will output a sufficiently high turn-on voltage (such as above the threshold voltage) to put the GaN power device into the on state.

[0058] 3. Current generation module

[0059] Function: After the GaN power device is turned on, a pulse current is generated and output between the source and drain metal layers according to the instructions of the control module.

[0060] Operation: The current generation module can output currents of different waveforms (such as square waves, sine waves, etc.) and amplitudes to simulate actual working scenarios or perform specific performance tests.

[0061] 4. Voltage measurement module

[0062] Function: Monitor and measure the voltage between the source and drain metal layers of GaN power devices in real time, and feed the measurement results back to the control module.

[0063] Operation: During the test, the voltage measurement module will continuously or at preset time intervals collect voltage data. These data reflect the voltage drop or voltage drop change of the device under different working conditions and are an important basis for evaluating device performance (including junction temperature).

[0064] 5. Determine the junction temperature of GaN power devices

[0065] The junction temperature of a GaN power device is usually closely related to its on-resistance (or channel resistance). As the junction temperature increases, the channel resistance increases, resulting in an increase in the voltage drop between the source and drain metal layers at the same current. Therefore, the junction temperature of a GaN power device can be estimated by the following steps:

[0066] Establish a model: Based on the specification or experimental data of the GaN power device, establish a mathematical relationship model between junction temperature and channel resistance (or voltage drop).

[0067] Data collection: During the test, the voltage measurement module is used to collect the source and drain metal layer voltage data under different current conditions.

[0068] Data analysis: Using the collected voltage data and the established model, the corresponding channel resistance value is calculated, and then the junction temperature of the GaN power device is estimated.

[0069] Feedback Adjustment: Based on the estimated junction temperature, the control module can adjust the voltage and current outputs to maintain the device within a safe operating temperature range or further explore its performance limits.

[0070] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A GaN power device structure, comprising an N-type SiC substrate (1), characterized in that: A buffer layer (2) is arranged at the upper end of the N-type SiC substrate (1); a metal is deposited at the upper end of the buffer layer (2) to form a drain metal layer (11); a conduction layer (3) formed of a highly doped N-type GaN layer is arranged at the upper end of the drain metal layer (11); a drift region (4) formed of a lightly doped N-type GaN layer is arranged at the upper end of the conduction layer (3); alternately arranged P-type GaN layers (5) are arranged in the drift region (4); the lower end (5) of each P-type GaN layer is in contact with the conduction layer (3); and the P-type GaN layer (5) is in contact with the conduction layer (3). The N-type GaN layers of the drift region (4) are arranged alternately to form a superjunction composite structure; a blocking layer (6) formed of a P-type GaN layer is provided at the upper end of the drift region (4); a source contact layer (7) formed of a highly doped N-type GaN layer is provided at the upper end of the blocking layer (6); a groove extending to the drift region (4) is etched downward from the upper end of the source contact layer (7); an insulating layer (8) is provided in the groove; a gate (9) is deposited at the upper end of the insulating layer (8); and a metal is deposited at the upper end of the source contact layer (7) to form a source (10).

2. A GaN power device structure according to claim 1, characterized in that: The buffer layer (2) is an N-type doped AlN layer.

3. A GaN power device structure according to claim 1, characterized in that: The insulating layer (8) uses SiO2 as the metal material.

4. A GaN power device structure according to claim 1, characterized in that: The gate (9) uses Ti as the metal material.

5. The GaN power device structure according to claim 1, characterized in that: The source electrode (10) uses Al as the metal material.

6. A GaN power device structure according to claim 1, characterized in that: The drain metal layer (11) uses Cu as the metal material.

7. A junction temperature testing device, used for testing the junction temperature of a GaN power device structure according to any one of claims 1 to 6, characterized in that: The invention comprises a control module (12), a voltage generating module (13), a current generating module (14) and a voltage measuring module (15); the voltage generating module (13) is respectively connected to the gate (9) and the control module (12); the current generating module (14) is connected to the two ends of the source (10) and the drain metal layer (11), and is also connected to the control module (12); the voltage measuring module (15) is connected to the two ends of the source (10) and the drain metal layer (11), and is also connected to the control module (12); the control module (12) is used to output corresponding control instructions to the voltage generating module (13), the current generating module (14) and the voltage measuring module (15), and to determine the junction temperature of the GaN power device according to the measured voltages at the two ends of the source (10) and the drain metal layer (11).

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