Power semiconductors (also known as power electronic devices) are used for power conversion and control current control. They are key components of power electronic systems and are used in power transmission and transformation and power consumption scenarios such as power supply, motor control, renewable energy, power transmission, and power traction.

In 2019, the global power device market scale was approximately US$40 billion, with an average compound growth rate of 5.1% over the past five years. Among them, China is the largest market, accounting for nearly 40%.

The semiconductor materials used in power devices are divided into three generations:

The first-generation semiconductor materials are simple materials such as silicon (Si) and germanium (Ge). Due to the mature technology and low production cost, silicon occupies more than 95% of semiconductor devices and is the main body of semiconductor materials today;

The second-generation semiconductor materials are compound materials such as gallium arsenide (GaAs). Gallium arsenide semiconductor has the advantages of high electron mobility, wider band gap than silicon, high withstand voltage, high frequency, etc., but it also has disadvantages such as weak mechanical strength, easy decomposition at high temperatures, slow growth speed, and high price. It is currently mainly used In the field of optoelectronics such as LED;

The third-generation semiconductor materials are silicon carbide (SiC), gallium nitride (GaN) and other wide band gap materials.

Improving energy efficiency (reducing energy consumption and loss) is the main direction of power semiconductor technology progress. The ideal goal is that the power semiconductor has no power consumption in the on state and no leakage current in the off state. Today, according to the IEA report, the world's electrical energy consumption accounts for 20% of the total electrical energy, which is a huge waste from the perspective of economic benefits and environmental protection. However, for power semiconductor devices made of traditional silicon materials, the power conversion efficiency has reached the theoretical limit.

The application of third-generation semiconductor materials represented by silicon carbide and gallium nitride has emerged, and has become the evolution direction of the next generation of power semiconductor technology. According to China's third-generation semiconductor industry technology innovation strategic alliance, the performance advantages of third-generation semiconductor materials include: high electronic drift speed, can reduce power conversion power consumption, improve energy efficiency; high band gap width, large critical breakdown voltage, Reduce the number of components required by the system under high-pressure operating conditions, promote the miniaturization and light weight of the system; high thermal conductivity, reduce the required cooling system.

Compared with gallium nitride, silicon carbide is more suitable for applications in power systems above 1,000V, including electric vehicles, charging piles, new energy power generation devices, high-speed rail power traction and other medium and high voltage scenarios. When the technology of using silicon substrates for gallium nitride devices is mature, it will have more cost advantages than silicon carbide devices using homogeneous substrates. In the future, in the medium and low voltage scenarios, devices made of silicon carbide and gallium nitride materials will compete.

At present, silicon carbide devices are mainly used for power supply and photovoltaic inverters, as well as limited electric vehicle industry applications. The main potential application market has not yet been opened.

From 2017 to 2019, the average compound growth rate of the global silicon carbide power device market was 39.7%. In 2019, the market size was 507 million US dollars, and the market penetration rate was still only 1.27%.

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Future growth potential: The rising demand for new energy vehicle applications will promote the growth of the silicon carbide device market

Public information from various channels is optimistic about the growth of the silicon carbide device market. It is estimated that in 2025, the global silicon carbide device market will exceed 3 billion U.S. dollars, with an average compound growth rate of 34.5% in the next five years, and continue to grow thereafter.

From the perspective of growth sources/downstream demand, in the foreseeable future, new energy vehicles (including supporting charging piles) will be the largest application scenario for silicon carbide devices, accounting for at least 50% of the total demand, and the growth rate far exceeds other markets.

In terms of breakdown, at present, silicon carbide devices are mainly used in OBC car chargers and DC-DC converters in electric vehicles, helping to increase the speed of car charging. At the end of 2018, more than 20 automobile manufacturers worldwide have used silicon carbide devices in OBC. However, its market value space is relatively limited.

The application of silicon carbide devices to the drive motor/inverter of an electric vehicle (ie its power system) can significantly increase the mileage, and the scale of potential applications is much larger than other applications. Using silicon carbide devices to drive motors can not only reduce power loss and improve power controllability, but also make the equipment smaller (about 50% reduction) and lighter in weight, thereby increasing the mileage of the car by 5-10%. Or correspondingly reduce the battery cost by 5%~10% (approximately US$200-600 per vehicle). Moreover, the use of silicon carbide devices can also reduce the cost of the refrigeration system and extend the service life of the power battery, which is beneficial and harmless. A rough estimate is that the potential value of the silicon carbide devices used on the drive motors of each electric vehicle may exceed the value of existing applications by more than 10 times.

The application trend of silicon carbide devices for driving motors has been clear. Currently, most car companies plan to use silicon carbide devices in their main inverters in the next few years. For cost reasons, silicon carbide devices were first deployed in high-end electric vehicles. Tesla is a pioneer in the application of silicon carbide devices. Its Model 3 drive motor is equipped with 24 650V/100A silicon carbide MOSFET modules. BYD's newly launched Han (high-performance version) in 2020 uses silicon carbide MOSFET motor control modules. Foreign component suppliers Bosch, ZF, and Delphi have also launched R&D plans for silicon carbide electric drive systems. In addition, the increase in power system voltage means faster charging. Starting with the Porsche Taycan, as the high-end electric vehicle battery pack voltage platform is upgraded from 400v to 800v, ​​the demand for silicon carbide modules will shift from 650v to 1200v.

In addition, the application of silicon carbide devices in the charging pile market will also grow rapidly. The popularization of new energy vehicles will drive the demand for charging pile construction, and there is currently a large gap at home and abroad. Due to its performance advantages, silicon carbide devices are widely used in high-power DC (fast charging) charging piles.

In addition to new energy vehicles, high withstand voltage devices for specific needs such as rail transit and UHV power grids are still in the development stage and are expected to be commercially possible after 2025.

However, because the process of silicon carbide is more complicated than silicon, and the added value is higher, downstream customers mainly use it for high-efficiency applications, and it is not expected to replace silicon in low-end applications.

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Technology development trend: The industry is breaking through the two development barriers of high cost and low technology maturity

As mentioned above, silicon carbide devices have outstanding performance advantages, clear application scenarios, and active investment by leading upstream and downstream enterprises in the industry chain, but the current market penetration rate is still low. The reason is that it is subject to the two barriers of high manufacturing cost and low technology maturity. Breaking these two barriers is the core of the direction of technological development. The four links of silicon carbide device manufacturing (substrate manufacturing, epitaxial manufacturing, chip manufacturing process, packaging and testing) have their own efforts.

1) The manufacturing cost of silicon carbide devices is high. At present, the cost of silicon carbide diodes and MOSFETs is about 2-3 times and 5-10 times that of similar silicon products. Downstream customers believe that the general price range for large-scale applications of silicon carbide devices should be about 1.5 times that of similar silicon devices. The main factor of high cost is the high price of raw materials, especially substrate wafers that account for 50% of the cost of standard silicon carbide devices.

The characteristics of silicon carbide raw materials determine the difficulty and cost of preparation higher than silicon wafers. In terms of preparation temperature, silicon carbide substrates need to be produced under high temperature equipment at 2500 degrees, while silicon crystals only need 1500 degrees. In terms of production cycle, silicon carbide wafers need about 7 to 10 days, while silicon ingots only need 2.5 days. ; In terms of commercial wafer size, silicon carbide wafers are currently mainly 4 inches and 6 inches, while silicon wafers used for power devices are mainly 8 inches, which means that the number of chips produced by a single silicon carbide wafer is small. The manufacturing cost of silicon carbide chips is relatively high.

Technology evolution direction: In terms of substrates, leading foreign companies are expected to start mass production of 8-inch wafers around 2022; in terms of epitaxy and devices, they will continue to increase production capacity and manufacturing yields.

2) The silicon carbide industry has not developed for a long time and needs more application verification. Unlike the silicon industry, silicon carbide has accumulated a very complete set of data in decades of research. Many performance conclusions of silicon carbide are derived from the properties of silicon, and many characteristic data need to be further verified.

In addition, the product portfolio of silicon carbide power devices is not yet complete. From the perspective of the entire power semiconductor market, there are various types of power devices, including diodes, MOSFETs, IGBTs, etc., which are suitable for different fields. But at present, the silicon carbide device market is still dominated by diodes, MOSFETs have not yet been widely promoted, and IGBTs are still being developed. Silicon carbide diodes are mainly used to replace silicon diodes with low structural complexity and are now commercialized on a large scale. In 2019, the silicon carbide device market for silicon carbide diodes accounted for 85%, which can be described as the most important silicon carbide device at present. Silicon carbide MOSFETs can replace silicon-based IGBTs, and large-scale applications are still limited by product performance stability and device maturity. The silicon carbide IGBT is still under research and development, and it is expected that prototypes of related devices will be seen in 5-10 years.

Technological evolution direction: In terms of devices, high withstand voltage devices above 3.3kv are being developed, and trench designs are introduced to improve device performance and reliability; in terms of packaging, the packaging process will be optimized to take advantage of the high temperature resistance of silicon carbide.

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Recommendations for promoting the development of domestic industries:

Strengthen top-level design, formulate plans, concentrate strength, develop technology, and lay a solid foundation

· Develop strategic plans, plan technological development routes, and explore ways and means to gather resources from all parties

· Mobilize government and capital, promote industrial clusters, concentrate and optimize innovation resources, and concentrate efforts to break through technical shortcomings in equipment, materials and devices

· Strengthen basic research, encourage original innovation, and provide industry with talent, technology, and creative supply

Improve the basic platforms for public R&D, services, and production applications in the industry chain

· Build an open national innovation technology center, an international public R&D and service platform, tackle core technologies and enrich innovation resources

· Build a test verification and application demonstration platform, improve product testing processes, assist enterprises in innovative applications, and strengthen systemic capabilities with application as the core

Improve the industrial ecological environment and grasp key points such as talents, technology, applications, and international cooperation

· Improve the talent system and cultivate leading talents in entrepreneurial innovation, engineering and technology

· Build an open and orderly technical standard system, strengthen patent operations, and actively participate in the formulation of international technical standards

· Promote international cooperation, increase scientific research exchanges with foreign industry, academia and research circles, and promote the establishment of overseas technology R&D and innovation centers