[Summary description] Power semiconductors (also known as power electronic devices) are used for electrical energy conversion, control current control, and are key components of power electronic systems, which are used in power supply, motor control, renewable energy, power transmission, power traction and other transmission and electricity scenarios.
Power semiconductors (also known as power electronic devices) are used for electrical energy conversion, control current control, and are key components of power electronic systems, which are used in power supply, motor control, renewable energy, power transmission, power traction and other transmission and electricity scenarios.
 
In 2019, the global power device market size was approximately $40 billion, with an average compound growth rate of 5.1% over the past five years.
Of these, China is the largest market, accounting for nearly 40%.
Semiconductor materials used in power devices are divided into three generations:
 
The first generation of semiconductor materials are silicon (Si), germanium (Ge) and other elemental materials.
Due to the mature process and low production cost, silicon accounts for more than 95% of semiconductor devices, and is the main body of semiconductor materials today.
 
The second generation of semiconductor materials are gallium arsenide (GaAs) and other compound materials.
Gallium arsenide semiconductor has the advantages of high electron mobility, larger bandgap than silicon, high voltage, high frequency, etc., but it also has the disadvantages of weak mechanical strength, easy decomposition at high temperature, slow growth rate, high price, etc., which is mainly used in the optoelectronic field such as LED.
 
The third generation semiconductor materials are silicon carbide (SiC), gallium nitride (GaN) and other wide band gap materials.
 
Improving energy utilization 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, 20% of the world's electricity is lost, which is a huge waste from both an economic and environmental point of view.
However, the conversion efficiency of power semiconductor devices made of traditional silicon materials has reached the theoretical limit.
 
The application of the third generation semiconductor materials represented by silicon carbide and gallium nitride has become the next generation of power semiconductor technology evolution direction.
According to China's third-generation semiconductor industry Technology Innovation strategic Alliance, the performance advantages of third-generation semiconductor materials include: high electron drift speed, which can reduce the power conversion power consumption and improve energy utilization efficiency;
High bandgap width, large critical breakdown voltage, reduce the number of devices required by the system under high voltage operating conditions, and promote the system miniaturization and lightweight;
High thermal conductivity reduces the cooling system required.
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.
Gallium nitride devices using silicon substrate technology is mature, compared with the use of homogeneous substrate silicon carbide devices, more cost advantages.
In the future, devices made of silicon carbide and gallium nitride materials will compete in low - and medium-voltage scenarios.
 
Currently, silicon carbide devices are mainly used in 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%, the market size was 507 million US dollars in 2019, and the market penetration rate was still only 1.27%, and the sharp corner was emerging.
02
Future growth potential: Rising demand for new energy vehicle applications will drive the growth of the silicon carbide device market
 
The public information of all channels is more 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 US dollars, with an average compound growth rate of up to 34.5% in the next 5 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 of silicon carbide devices, accounting for at least 50% of the total demand, and the growth rate is far higher than other markets.
At present, silicon carbide devices are mainly used in electric vehicles for OBC on-board chargers and DC-DC converters, which help to improve car charging speed.
By the end of 2018, more than 20 automotive manufacturers around the world were using silicon carbide devices in OBC.
However, its market value space is more limited.
The application of silicon carbide devices in the drive motor/inverter (i.e. its power system) of electric vehicles can significantly improve the driving range, and the potential application scale is much larger than other applications.
The silicon carbide device used to drive the motor can reduce power loss, improve power controllability, but also make the device smaller (reduced by about 50%), lighter weight, so that the vehicle mileage increase by 5 to 10%, or the corresponding reduction of 5 to 10% of the battery cost (about $200 to $600 per vehicle).
In addition, 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.
It is roughly estimated that the potential value of silicon carbide devices used in each electric vehicle drive motor is more than 10 times the value of existing applications.
 
The application trend of silicon carbide devices driving motors has been clear.
At present, most car companies are planning to use silicon carbide devices in the main inverter in the next few years.
Due to cost factors, silicon carbide devices are first configured in high-end electric vehicles, Tesla is a pioneer in the application of silicon carbide devices, and its Model3 drive motor is equipped with 24 650V/100A silicon carbide MOSFET modules.
Byd's new Han (High-Performance Edition) in 2020 uses a silicon carbide MOSFET motor control module.
Foreign parts suppliers Bosch, ZF, Delphi have also launched silicon carbide electric drive system research and development plans.
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 popularity of new energy vehicles will drive the demand for charging pile construction, and there is a large gap at home and abroad.
Due to its performance advantages, silicon carbide devices are widely used in high-power DC (fast charge) charging piles.
 
In addition to new energy vehicles, high-voltage devices for specific needs such as rail transit and UHV power grids are still in the development stage, and are expected to have commercial possibilities after 2025.
 
However, because the process of silicon carbide is more complex than silicon and has higher added value, downstream customers mainly use it for high-benefit applications, and it is not expected to replace silicon in the low-end field.
03
Technology development trends: The industry is breaking down the two major 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 upstream and downstream leading enterprises in the industry chain, but the current market penetration rate is still low.
The reason is that it is subject to the two major barriers of high manufacturing costs 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 production, epitaxial production, chip process, packaging and testing) have their own strengths.
 
1) Silicon carbide devices are expensive to manufacture.
At present, the cost of silicon carbide diodes and MOSFET is about 2-3 times and 5-10 times that of similar silicon products, and downstream customers believe that the general price range of large-scale applications of silicon carbide devices should be about 1.5 times that of similar silicon devices.
The main factor in the high cost is the high price of raw materials, especially substrate wafers, which 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 substrate needs to be produced at 2500 degrees high temperature equipment, while silicon crystal only needs 1500 degrees;
In terms of production cycle, it takes about 7 to 10 days for silicon carbide wafers, and only 2 and a half days for silicon rods.
In terms of commercial wafer size, at present, silicon carbide wafers are 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 silicon carbide single wafer is small and the manufacturing cost of silicon carbide chips is high.
 
Technology evolution direction: In terms of substrate, foreign leading enterprises are expected to start mass production of 8-inch chips around 2022;
In terms of epitaxy and devices, it will continue to increase production capacity and manufacturing yield.
 
2) Silicon carbide industry development time is not long, need more application verification.
Silicon carbide is not like the silicon industry, which has accumulated a very complete set of data in decades of research.
Many properties of silicon carbide are derived from the properties of silicon, and many properties data need to be further demonstrated.
 
In addition, the product portfolio of silicon carbide power devices is not yet perfect.
From the perspective of the entire power semiconductor market, there are various types of power devices, mainly including diodes, MOSFETs, IGBTs, etc., which are suitable for different fields.
However, at present, the silicon carbide device market is still dominated by diodes, MOSFET has not been promoted on a large scale, and IGBT is still being developed.
Silicon carbide diodes are mainly used to replace silicon diodes, the structural complexity is low, and it has been commercialized on a large scale, and the silicon carbide device market share of silicon carbide diodes in 2019 reached 85%, which can be described as the most important silicon carbide devices at present.
Silicon carbide MOSFETs can replace silicon-based IGBTs, and large-scale applications are still limited by product performance stability and device maturity.
Silicon carbide IGBT is still under development, and it is expected that the relevant device prototype will be seen in 5-10 years.
 
Technology evolution direction: In terms of devices, high voltage devices above 3.3kv are being developed, and groove design is 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.
04
Suggestions for promoting the development of domestic industries:
 
Strengthen top-level design, formulate plans, concentrate resources, develop technology, and consolidate the foundation
 
· Formulate strategic plans, plan technological development routes, and explore ways and methods that can bring together resources of all parties
· Mobilize government and capital to promote industrial clusters, centralize and optimize innovation resources, and concentrate efforts to overcome technical gaps in equipment, materials, and devices
· Strengthen basic research, encourage original innovation, and provide talent, technology, and creative supply to the industry
 
Improve the industrial chain public research and development, services, and production applications and other basic platforms
 
· Build an open national innovation technology center and an international public R & D and service platform to tackle core technologies and enrich innovation resources
· Build test verification and application demonstration platforms, improve product testing processes, assist enterprises in innovative applications, and strengthen application-centered systematic capabilities
 
We will improve the industrial ecological environment and focus on key points such as talent, technology, application, and international cooperation
 
· Improve the talent system to cultivate leading talents in entrepreneurship, innovation, engineering and technology
· Build an open and orderly technical standard system, strengthen patent operation, and actively participate in the formulation of international technical standards
· Promote international cooperation, increase scientific research exchanges with foreign industry, universities and research communities, and promote the establishment of overseas technology research and development and innovation centers