A few days ago, Mr. Chen Ziying, Marketing Director of Infineon Industrial Power Control Division Greater China, and Mr. Cheng Wentao, Director of Greater China Application Marketing of Infineon Technology Power and Sensing Division, discussed the value of third-generation semiconductor technology and industrial development in media interviews. In-depth interpretation of technology trends.

Entering the post-Moore era, on the one hand, human society is pursuing to improve the quality of life with technologies such as the Internet of Everything, artificial intelligence, big data, smart cities, and intelligent transportation, and the pace of development is accelerating. On the other hand, improving the global climate through low-carbon life has increasingly become a consensus.

At present, about one-third of the global energy demand is electricity demand. The increasing energy demand, the depletion of fossil fuel resources, and climate change and other issues require us to find smarter and more efficient energy production, transmission and distribution. , storage and use.

Across the entire energy conversion chain, the energy-saving potential of third-generation semiconductor technologies can greatly contribute to achieving long-term global energy-saving goals. In addition, wide bandgap products and solutions are beneficial to improve efficiency, increase density, reduce size, reduce weight, and reduce total cost, so they will be widely used in transportation, data centers, smart buildings, home appliances, personal Electronic devices, etc. Contribute to energy efficiency improvement in application scenarios.

For example, in the application of power electronic systems, high-speed power devices with a withstand voltage of more than 1200V have been expected to appear, and such devices are not SiC MOSFETs today. The silicon MOSFET is mainly used in the low and medium power fields below 650V.

In addition to high speed, silicon carbide also has the characteristics of high thermal conductivity, high breakdown field strength, high saturation electron drift rate, etc., and is especially suitable for applications with high requirements for harsh conditions such as high temperature, high power, high voltage, high frequency and radiation resistance. .

Power density is another important aspect of device technology value. The chip area of ​​SiC MOSFET is much smaller than that of IGBT. For example, the chip size of 100A/1200V SiC MOSFET is about one-fifth of the sum of IGBT and freewheeling diode. Therefore, in high power density and high speed motor drive applications, the value of SiC MOSFETs can be well represented, including 650V SiC MOSFETs.

In terms of high voltage resistance, SiC high-speed devices with high voltages above 1200V can improve system performance and system power density by increasing the switching frequency of the system. Here are two examples:

If Si MOSFET is used for the power unit of the DC charging pile of electric vehicles, two-stage LLCs need to be connected in series, and the circuit is complicated. If SiC MOSFET is used, a single-stage LLC can be realized, thereby greatly improving the single-unit power of the power unit of the charging pile.

For flyback power supplies in three-phase systems, 1700V SiC MOSFETs are also the perfect solution, reducing losses by 50% and improving efficiency by 2.5% compared to 1500V silicon MOSFETs.

In terms of reliability and quality assurance, there are two types of SiC devices: planar gate and trench gate. Infineon’s trench gate SiC MOSFET can well avoid the reliability problem of the gate oxide layer of the planar gate, and the power density is also low. higher.

It is precisely because of these excellent properties of SiC MOSFET that it has corresponding applications in photovoltaic inverters, UPS, ESS, electric vehicle charging, fuel cells, motor drives and electric vehicles.

However, will silicon carbide be the ultimate solution for all applications?

As we all know, IGBT technology, the representative of silicon-based power semiconductors, has encountered some difficulties in further improving performance. The switching loss and the reduction of the on-saturated voltage drop are mutually restricted, and the space for reducing the loss and improving the efficiency is getting smaller and smaller, so the industry began to hope that SiC can become a disruptive technology. However, this view is not very comprehensive. First of all, the technology of silicon-based IGBTs represented by Infineon is also progressing. TRENCHSTOP?5 and IGBT7 using micro-trench technology are new milestones. With the advancement of packaging technology, the performance and power density of IGBT devices have become more and more higher. At the same time, products developed for different applications can be specially optimized to improve the performance of silicon devices in the system, thereby improving system performance and cost performance. Therefore, the development process of third-generation semiconductors must be accompanied by silicon devices. Along with technological development, there are also considerations of large-scale commercialization value factors for different applications. It is expected that third-generation devices will soon be used in all applications. Replacing silicon devices in the scenario is not realistic.

　　The road to industrialization

Infineon began to develop SiC power devices in 1992, established a 2-inch production line in 1998, and launched its first SiC product in 2001, marking its 20th anniversary this year. In the past 20 years, silicon carbide technology has been progressing. In 2006, diodes using MPS technology were released to solve the pain point of inrush current resistance; in 2013, the fifth generation of thin wafer technology diodes was launched. From 2014 to 2017, SiC JFET, the fifth generation 1200V diode, 6″ technology and SiC trench gate MOSFET.

From the development history of Infineon SiC devices, we can see the development history and trend of SiC technology. We are well aware of the reliability of planar gates. Before the development of trench gates is completed, SiC JFET is a transitional product to help customers quickly enter the field of SiC applications. From the perspective of technology development trends, SiC MOSFETs need to switch to trench gates more urgently than IGBTs. In addition to power density considerations, they pay more attention to reliability issues.

At the industrial level, when the time comes to the third decade of the 21st century, the entire third-generation semiconductor industry pattern has undergone tremendous changes compared with the initial stage of development. Specifically, the silicon carbide industry is accelerating vertical integration, and the gallium nitride industry has formed a model in which IDMs and design companies and foundries coexist. These all show that the third-generation semiconductor industry has entered a stage of large-scale and high-speed development.

Of course, compared with the silicon-based device industry, the third-generation semiconductor industry has a relatively short development time, and there is still a long way to go in terms of standardization and maturity, especially in terms of quality and long-term reliability. research and validation work to be done. Infineon has rich experience and recognized advantages in standardization, quality management and reliability. At the beginning of the development of third-generation devices, Infineon has continued to invest a lot of resources, and has conducted in-depth analysis, research and optimization. The steady development of the third-generation semiconductor industry. To this end, Infineon has published the “Silicon Carbide Reliability White Paper”, which discusses how Infineon controls and guarantees the reliability of SiC-based power semiconductor devices.

　　Results and Trends

At present, there are many areas worth paying attention to at the technical level of third-generation semiconductors. For example, the cold cutting technology of silicon carbide wafers, device channel structure optimization, GaN gate structure optimization, long-term reliability model, transplantation of mature silicon power device modules and packaging technology, etc., will all contribute to the long-term development of third-generation semiconductors. have a profound impact. These areas are also the areas that Infineon focuses on and excels in the development of its third-generation semiconductor products.

Specifically, Infineon acquired Dresden-based startup Siltectra in 2018. The company’s innovative Cold Split technology efficiently processes crystalline material with minimal material loss. Infineon uses this cold dicing technology to cut silicon carbide wafers, which can double the number of chips produced from a single wafer, thereby effectively reducing the cost of SiC.

In terms of low and medium power SiC devices, last year Infineon released the 650V CoolSiC™ MOSFET in TO-247 package based on the 1200V series, which further improved the product portfolio. SMD packaged 650V product series is currently under development. In terms of gallium nitride, in May this year we launched the CoolGaN® IPS series of integrated power stage products, the latest addition to our many WBG power components portfolio. IPS’ basic product portfolio includes half-bridge and single-channel products targeting low to medium power applications such as chargers, adapters and other switching power supplies. The representative product 600V CoolGaN? Half-bridge IPS IGI60F1414A1L, 8×8 QFN-28 package, can provide extremely high power density for the system. This product includes two 140mΩ/600V enhancement mode HEMT switches and GaN-specific isolated high- and low-side drivers in the EiceDRIVER™ family.

In terms of high voltage, silicon carbide products will continue to develop in the direction of exerting their main characteristics, with higher withstand voltages, and products of 2-3kV level will be launched one after another.

At the same time, Infineon will use mature Module technology, low parasitic inductance, low thermal resistance packaging technology, etc. to develop corresponding products for different applications. For example, low parasitic inductance packaging can make SiC devices better at high-speed performance. Although the cost of low thermal resistance packaging technology is slightly higher, it can effectively improve the current output capability of the device, thereby actually reducing the cost per unit power density.