Recently, the State-owned Assets Supervision and Administration Commission of the State Council issued the "Recommended Catalogue of Scientific and Technological Innovation Achievements of Central Enterprises (2020 Edition)" to the whole society, including core electronic components, key components, analysis and testing instruments and high-end equipment, including 8 fields and 178 scientific and technological innovation achievements. . The 3300 volt (V) insulated gate bipolar transistor (IGBT) chips and modules developed by the Global Energy Internet Research Institute Co., Ltd. (hereinafter referred to as the Joint Research Institute) are impressively listed. After 4 years, the research team of the Joint Research Institute broke through the technical bottlenecks that restricted the development of domestic high-voltage IGBTs, such as poor robustness and low reliability, and broke the foreign technology monopoly.
Previously, the national key R&D project "key technology and application of customized ultra-high power IGBT for flexible DC transmission equipment crimping" led by the team passed the comprehensive performance evaluation organized by the Ministry of Industry and Information Technology. The project independently developed 4500V/3000A low on-state voltage drop and 3300V/3000A high turn-off capacity IGBT devices that meet the requirements of flexible DC transmission equipment, which solved the problem of the lack of high-voltage and large-capacity crimp type IGBT chips and devices.
Involves multiple links, requiring joint research from multiple industries
The development cycle of high-voltage IGBT chips and devices is long, involving materials, chip design, chip technology, device packaging and testing, and requires cross-disciplinary integration and multi-industry collaborative development.
"Currently, there are four main technical bottlenecks in the development of high-voltage IGBT devices for power system applications. One is the preparation technology of high-resistivity substrate materials for high-voltage chips. The doping uniformity and stability of large-size wafers are difficult to meet the high-voltage requirements. IGBT and FRD chip development needs; second, the lack of key process capabilities for high-voltage chips, and the lack of high-end process processing capabilities to improve chip performance, which cannot meet the processing needs of high-voltage IGBT chips for power systems; third, the packaging design system and process capabilities are difficult to meet high-voltage devices Packaging requirements, especially crimp-type device packaging, have insufficient research in packaging insulation systems, multi-chip parallel current sharing and pressure equalization control; fourth, the overall reliability and robustness of high-voltage IGBT devices are far behind foreign advanced levels. It has not been verified by the long-term application of power system equipment and engineering." Wu Junmin, director of the Power Semiconductor Research Institute of the Joint Research Institute, said in an interview with a reporter from the Science and Technology Daily.
IGBT chip size is small, microstructure is complex, and there are many structure and process parameters that affect chip performance. At the same time, IGBT chip on-state voltage drop, turn-off loss and over-current turn-off capability are mutually restricted. The comprehensive optimization between the three is in the process of tackling key problems. The most difficult technology to break through.
Will be extended to offshore flexible DC transmission and other fields
"Faced with technical difficulties, the research team of the Joint Research Institute established a youth commando team, which used a combination of theoretical analysis, simulation design and experimental verification to optimize the design of the front cell structure and the back buffer layer structure of the IGBT chip, and develop carrier enhancement Key technologies such as layer, back buffer layer and ultra-thick polyimide passivation, and finally developed a high turn-off capability IGBT chip for power system applications, which achieved the on-state voltage drop, turn-off loss and over-current turn-off of the IGBT chip. The comprehensive optimization of the breaking capacity, the overall performance has reached the international advanced level." Wu Junmin said.
The project leader and deputy director of the Institute of Power Semiconductors of the Joint Research Institute, Jin Rui, told the reporter of Science and Technology Daily that in terms of chip technology, the team has overcome the technical problem of backside laser annealing uniformity control; mastered the impact of backside buffer layer doping on chip characteristics Influencing law, a three-dimensional local carrier lifetime control method is proposed. Compared with similar products in the world, the overall performance of the chip has reached the international advanced level.
"In terms of crimp packaging technology, based on the tolerance compensation technology of multiple disc spring components in series, the team proposed an elastic crimp packaging structure suitable for parallel IGBT chips, breaking through the pressure equalization control technology of large-scale parallel IGBT chips. , Realized the crimping and packaging of hundreds of chips in parallel; combining the characteristics of the packaging process and the characteristics of the insulating material, the package insulation gap, the packaging insulation material parameters and the influence of the packaging process parameters on the insulation level of the device were obtained, and the crimp packaging structure was proposed. The package insulation scheme of the company has mastered the potting process of distributed glue injection and periodic degassing; it has mastered the high-voltage non-destructive testing and screening methods of four levels: wafer level, chip level, sub-unit level, and device level. Unit and device testing and screening equipment supports the development of crimp packaging devices." Jin Rui said.
Jin Rui said that in the future, self-developed high-voltage IGBT chips and modules will be promoted and applied to offshore flexible DC transmission, unified power flow controllers and other fields to support the construction of "double high" power systems and help the goal of "carbon peak and carbon neutrality"