“The power device industry has developed to the IGBT (insulator gate bipolar transistor) stage. The performance of silicon-based devices has long been close to the limit, and the marginal benefits are getting higher and higher. However, the semiconductor material device industry chain is still very concerned about high-power, high-frequency conversion, high-temperature reality. There are more and more requirements for operation and high power, so wide-bandgap power devices with third-generation semiconductor devices such as SiC (carbon-carbon composite material) and GaN (gallium nitride) as the key have become a hot spot in scientific research networks. With the new development prospects, and gradually enter the application of mass production.
The power device industry has developed to the IGBT (insulator gate bipolar transistor) stage. The performance of silicon-based devices has long been close to the limit, and the marginal benefits are getting higher and higher. However, the semiconductor material device industry chain is still very concerned about high-power, high-frequency conversion, high-temperature reality. There are more and more requirements for operation and high power, so wide-bandgap power devices with third-generation semiconductor devices such as SiC (carbon-carbon composite material) and GaN (gallium nitride) as the key have become a hot spot in scientific research networks. With the new development prospects, and gradually enter the application of mass production.
SiC power device performance advantages
The development trend of SiC power semiconductors has improved the hard power switching characteristics of output power switching devices. The pressure resistance can reach hundreds of thousands of volts, and the high temperature resistance can reach above 500 °C.
(1) The wide band gap can greatly reduce leakage current, thereby reducing the loss of high-power devices;
(2) High breakdown field strength can improve the compressive working ability and current strength of power devices, and reduce overall specifications;
(3) The high thermal conductivity can improve the heat-resistant working ability, which is conducive to the heat removal of the device, reducing the volume of the cooling equipment, improving the processing speed and increasing the power;
(4) Strong radiation protection work ability, more suitable for use under irradiance standards such as alien planets. Theoretically, SiC devices are ideal raw materials for the close combination of high voltage, high temperature, high frequency, high power and radiation protection. They are mainly used in places with high power, and can complete the miniaturization and integration of control modules and software systems to improve power. and system software efficient.
Core Technology of SiC Power Devices
The production and production industry chain of carbon-carbon composite semiconductor power devices involves heat production, production, production, Ning, haze, Zheng Chuang, residence, printing, skeleton, and system application, and the whole industry chain involves many stages. Such as chip processing, program module design, etc. Compared with the traditional silicon-based application technology, the manufacturing of carbon-carbon composite semiconductor power devices has many challenges in key factors.
Substrate and Epitaxy
The substrate is the basis of power devices, because most of the production lines of Si-based power device manufacturers at this stage are suitable for wafers above 4 inches, so the technical improvement of SiC substrates of 4, 6 inches and above is SiC power devices. Necessary for large-scale deployment in all key industries.
The most commonly used method for single crystal growth of SiC is the physical liquid phase transfer method, but the disadvantage of the SiC-SiO2 interface is that the relative density is high, and the electron density of the safe channel Electronic device is low, resulting in a decrease in the performance and stability of the semiconductor material, which cannot reflect the SiC raw material. The advantages. With the technical development trend, according to the unique gate air oxidation process or the trench structure, 4- and 6-inch chips with basically zero relative density of visible flow of micro-tubes can be produced, and the 5.5-inch chip has also begun to be produced. Research and development, but the cost is relatively high. At this stage, the products on the market are still dominated by 4-inch single crystal substrates.
At the level of epitaxial raw materials, SiC uses homogenous epitaxial growth and development technology. The machinery and equipment and growth and development technology are relatively complete, and SiC epitaxial raw materials exceeding 100-200 μm can be grown and developed. The urgent thing to be dealt with in the epitaxial growth and development is the growth defect. problem.
Among the SiC diodes that first completed industrial development, the highest quality index is SiCSBD. SBD has a PN junction Schottky barrier composite structure, which can clear the limit of the maximum blocking voltage due to the amount of tunneling current, and make full use of the SiC critical value to penetrate The advantage of high field strength.
Research Network Hotspots of SiC Power Devices
SiC power modules are divided into hybrid SiC control modules and full SiC power modules. Compared with the product of SiIGBT control module with the same rated voltage, the hybrid SiC power module can significantly improve the output power and greatly reduce the switching loss. The full SiC power module completes the integrated sealing of SiCSBD and SiCMOSFET after improving the processing technology standard and device structure and improving the crystal quality, which solves the problem that the output power conversion loss of the high-voltage SiIGBT control module is very large. The field components are miniaturized in the field, but the cost is relatively high.
Seal b technical
The electrical, thermal and thermomechanical equipment problems that must be involved in the whole sealing process lie in the rated voltage and current level of the device. The traditional output power sealing method is the limiting factor to achieve the performance advantages of SiC power devices.
The encapsulation raw materials of SiC power devices should meet the following standard requirements:
(1) It has excellent heat transfer properties;
(2) It has the characteristics of high-quality insulating layer;
(3) The thermal expansion coefficient is small, which is consistent with the thermal expansion coefficient of SiC semiconductor devices;
(4) Heat-resistant, stable for a long time in a high-temperature natural environment above 300 °C in a gas atmosphere.
With the further improvement of various technologies in the entire industry chain of SiC power devices, various SiC power devices will be greatly improved in terms of yield, stability and cost in the future, and then enter the link of all-round application promotion. , will lead to new reforms in power electronics technology.