Silicon carbide semiconductor materials
The third generation of semiconductors has superior performance and wider application scenarios. As the basis for the development of electronic information technology, semiconductor materials have gone through several generations of changes. With the higher requirements of application scenarios, the third-generation semiconductor materials, represented by silicon carbide and gallium nitride, have gradually entered the industrialization and accelerated release phase. Compared with the previous two generations, silicon carbide has superior performance such as high voltage resistance, high temperature resistance and low loss, and is widely used in making high temperature, high frequency, high power and radiation resistant electronic devices.
Silicon carbide devices have a wide range of applications. Because of its high thermal conductivity, high breakdown electric field strength and high current density, semiconductor devices based on silicon carbide materials can be used in many industrial fields such as automobiles, charging devices, portable power supplies, communication devices, robotic arms, and flying machines. The scope of its application is becoming more and more popular and deepening, is a very wide range of application prospects, very valuable materials.
Analysis of the advantages of silicon carbide
The forbidden band width of the third generation semiconductor material is much larger than the first two generations. The first and second generations of semiconductors are narrow band gap semiconductors, while from the third generation of semiconductors, wide band (band gap greater than 2.2eV) semiconductor materials began to be used in large numbers. Silicon carbide, as a typical representative of third-generation semiconductors, has more than 200 spatial structures, and different structures correspond to different band gap values, generally between 2.4eV and 3.35eV. In addition to wide band, silicon carbide materials also have the advantages of high breakdown field strength, high saturation drift rate and high stability, and maximum power.
Wide band: improve material stability and breakdown field strength
The forbidden band width determines the material properties, wide forbidden band to improve better performance. The wide band width is an important indicator of semiconductor performance. A wider band means higher excitation requirements, i.e., more difficult formation of electrons and holes, which results in wide-bandgap semiconductors that maintain insulator-like properties when they are not required to work, which also makes them more stable, and a wide band also helps improve the breakdown electric field strength, which in turn enhances the ability to withstand the operating environment, as reflected in In the better heat and high voltage resistance, radiation resistance.
The high energy difference between the conduction band and the valence band in the wide band system reduces the compounding rate of electrons and holes after excitation, which allows more electrons and holes to be used for conductivity or heat transfer, which is one of the reasons for the stronger thermal and electrical conductivity of silicon carbide.
Based on these characteristics, silicon carbide devices can operate at higher intensities and are also able to dissipate heat more quickly, with higher ultimate operating temperatures. The high-temperature resistance characteristics can lead to a significant increase in power density while reducing the requirements for heat dissipation systems, allowing for lighter and smaller terminals. The high forbidden band width of silicon carbide also allows silicon carbide devices to leak significantly less current than silicon devices, thereby reducing power loss; silicon carbide devices do not have current trailing during the shutdown process, resulting in low switching losses and significantly increasing the switching frequency of practical applications.
High Breakdown Voltage: Bringing Greater Operating Range and Power Range
The higher the breakdown voltage, the larger the operating range and power range. Breakdown voltage refers to the voltage at which the dielectric breaks down. For semiconductors, once the breakdown voltage is reached, the semiconductor loses its dielectric properties and becomes inoperable due to the destruction of its internal structure, which is similar to that of a conductor. Therefore, a higher breakdown field means a larger operating range and power range, i.e., the higher the breakdown field, the better.
Silicon carbide devices are more powerful, smaller, and have lower energy losses. Because of its higher breakdown voltage, silicon carbide can be widely used in the preparation of high-power devices, an advantage that cannot be replaced by silicon-based semiconductors. The higher breakdown of silicon carbide allows silicon carbide power devices to have thinner and more heavily doped barrier layers, which allows the use of silicon carbide materials to make the devices thinner for the same requirements, which can serve to save space and increase the unit energy density. In addition, the high breakdown field also allows the silicon carbide to have a lower on-resistance in the external voltage, and a lower on-resistance means lower energy loss.
High saturation drift rate: less energy loss
Silicon carbide has a higher saturation drift rate due to its internal structure. Theoretically, the drift velocity can be increased indefinitely with the increase of the external electric field, but in practice, as the applied electric field increases, the collision between carriers inside the material also increases, so there is a saturation drift velocity. In the case of silicon carbide, the internal structure is very good at buffering collisions, so it has a higher saturation drift rate.
The high saturation drift rate results in less energy loss. A high saturation drift rate means faster carrier migration and lower resistance. This also results in much lower energy losses in silicon carbide materials. Compared to silicon, a silicon carbide-based MOSFET of the same size has 1/200 lower on-resistance and 1/10 smaller size than a silicon-based MOSFET, and an inverter using a silicon carbide-based MOSFET of the same size has less than 1/4 of the total energy loss compared to a silicon-based IGBT. These characteristics provide a strong support for the application of silicon carbide materials in PV inverters and high frequency devices.
Silicon carbide industry chain
Foreign manufacturers are mostly laid out in IDM mode, while domestic companies focus on individual links. Silicon carbide industry chain can be divided into: substrate, epitaxy, device, and end-use. Most foreign companies are in the IDM mode, such as Wolfspeed, Rohm and STMicroelectronics (ST), while domestic companies focus on single link manufacturing, such as Tianke Heda and Tianyue Advanced in the substrate field, Hantian Tiancheng and Dongguan Tiandian in the epitaxial field, and Starr Peninsula and Tyco Tianrun in the device field.
Substrates and epitaxy account for 70% of the cost of silicon carbide devices. Due to the difficulty of material preparation, low yield rate and small production capacity, the value of the current industry chain is concentrated in the substrate and epitaxial parts, with the front-end parts accounting for 47% and 23% of the cost of silicon carbide devices, while the back-end design, manufacturing and packaging segments account for only 30%.
Downstream use of silicon carbide
New Energy Vehicles
The new energy vehicle sector will bring huge increment for SiC power devices. In new energy vehicles, SiC devices are mainly used in main drive inverters, OBC (on-board chargers), DC-DC on-board power converters and high-power DCDC charging devices. With the introduction of 800V voltage platforms by major vehicle manufacturers, the main drive inverter of motor controllers will inevitably be replaced by SiC-MOS with silicon-based IGBTs to meet the demand of high current and high voltage, which will bring huge growth space.
The power module in the motor controller accounts for 8% of the cost of the vehicle. It is responsible for converting the high-voltage DC power output from the power battery into three-phase AC power with variable frequency and current, supplying power to the drive motor, changing the speed and torque of the motor, and rectifying the three-phase AC power from the motor into DC power to charge the power battery during energy recovery. The power module accounts for 41% of its cost, or 8% of the vehicle cost.
The benefits of using silicon carbide devices include:
1) Improved acceleration. The use of silicon carbide devices allows the drive motor to withstand higher input power at low speeds, and because of its high thermal performance, it is not afraid of thermal effects and power losses caused by excessive current. This allows the drive motor to deliver more torque when the vehicle starts, resulting in greater acceleration.
SiC devices can be used to increase the range of electric vehicles by reducing losses in both on/off dimensions. According to Infineon’s research data, SiC-MOS turn-off loss is about 20% of Si-IGBT at 25°C junction temperature, and 10% of Si-IGBT at 175°C junction temperature. Overall, the use of SiC devices in new energy vehicles can increase the range by 5-10%.
3) Lightweighting. Thanks to the superior performance of SiC, SiC devices can reduce the size in the following aspects: 1) smaller package size, 2) less filters and passive components such as transformers, capacitors, inductors, etc., 3) less heat sink size, and 4) less battery capacity within the same range. The SiC inverter designed by Rohm, for example, reduces the size of the main inverter by 43% and the weight by 6 kg by using all SiC modules.
4) Reduce system cost. Currently, SiC devices are 4-6 times more expensive than silicon-based devices, but the use of SiC devices has resulted in a significant reduction in battery cost and an increase in range, which in turn has reduced the overall vehicle cost. The cost increase for the SiC-MOS drive inverter is about $75-$200, but the cost savings from the battery, passive components, and cooling system is $525-$850, a significant reduction in systemic costs. For the same mileage, the SiC inverter can save at least $200 per vehicle.
Photovoltaic Inverters
Silicon carbide power devices can improve the conversion efficiency of PV inverters and reduce energy losses. In photovoltaic power generation, conventional inverters based on silicon-based devices currently account for about 10% of the system cost, but are one of the main sources of system energy losses. By using SiC-MOS as the base material, the conversion efficiency of PV inverters can be increased from 96% to more than 99%, energy loss can be reduced by more than 50%, and equipment cycle life can be increased by 50 times, thus reducing system size, increasing power density, extending device life, and reducing production cost. High efficiency, high power density, high reliability and low cost are the future trends of PV inverters. Silicon carbide products are expected to gradually replace silicon based devices in string and centralized PV inverters. At present, there are few domestic applications of silicon carbide PV inverters in the PV field, but there are already PV inverter companies around the world that are using silicon carbide PV inverters, such as the TLM series from Ingeteam in Spain.
Rail Transportation
In rail transportation, power semiconductor devices are widely used in rail vehicles, including traction converters, auxiliary converters, main and auxiliary converters, power electronic transformers, and power chargers. Among them, the traction converter is the core equipment of the high-power AC transmission system of locomotives. The application of silicon carbide devices in rail transit traction converters can greatly exert the high temperature, high frequency and low loss characteristics of silicon carbide devices, improve the efficiency of traction converter devices, meet the demand for high-capacity, lightweight and energy-saving traction converter devices for rail transit, and improve the overall efficiency of the system.
Smart Grid
In the smart grid, compared with other power electronic devices, the power system requires higher voltage, higher power capacity and higher reliability. DC transmission, high-voltage DC transmission and power distribution systems to promote the development and change of smart grid.
RF field
In RF devices, GaN RF devices based on silicon carbide substrate have the advantages of high thermal conductivity of silicon carbide and high power RF output of GaN in high frequency band, and break through the inherent defects of GaAs and silicon-based LDMOS devices to meet the requirements of 5G communication for high frequency performance and high power processing capability. GaN-based RF devices have become the mainstream technology route for 5G power amplifiers, especially for macro base station power amplifiers.
Calculation of the global market space of silicon carbide substrate
Silicon carbide substrates are essential for the preparation of silicon carbide devices and are currently the most costly part of silicon carbide devices. Here, we estimate the global market space and substrate demand for silicon carbide substrates from 2021 to 2025 in the field of new energy vehicles and photovoltaics, and forecast the total market space and substrate demand for silicon carbide substrates with this reference.
New energy vehicles: 25 years demand may reach 3 million pieces, the market space of more than 10 billion yuan
For the new energy vehicle market forecast, we make the following assumptions on key parameters:
The current average price of 6-inch silicon carbide is 1000 U.S. dollars, about 6400 yuan / piece, due to the future development of the technical route on the 6-inch and the formation of further economies of scale, silicon carbide prices are expected to show a general trend of reduction, for the specific price trend, we 2021-2025 substrate price decline in the following three assumptions:
- 1) 10% reduction;
- 2) 15% reduction;
- 3) 20% reduction.
The number of substrates consumed per vehicle: Considering the future price decline will gradually increase the application of silicon carbide in new energy vehicles, based on the current Model 3 single vehicle with 48 silicon carbide MOSFET chips, the number of 6-inch substrates used in a single vehicle is about 0.16 pieces, and then gradually grow to 0.4 pieces in 2025.
Penetration rate: The penetration rate is defined as the percentage of new energy vehicle sales using SiC devices in the total new energy vehicle sales. 14% penetration rate in 2021 and 6% penetration rate growth is expected from 2021-2025.
Combined with the above data and assumptions, in the 10%/15%/20% price reduction is expected, the market of silicon carbide substrates in the field of new energy vehicles may reach 12.8/10.2/80 billion yuan, and the corresponding substrate demand will reach 3.04 million pieces.
Photovoltaic field: 25 years demand or more than 500,000 pieces, the market space of 2 billion yuan
The global new installed capacity: silicon carbide substrates are mainly used in PV inverters in the PV industry, with global installed capacity of 137GW in 2020 and expected to exceed 400GW in 2025, based on 400GW as a reference. 2021 data is converted from relevant data in Sunshine Power’s annual report, which is about 156GW.
IGBT cost ratio: According to the data disclosed in the prospectus, the cost ratio of silicon-based IGBT is about 10% of the total cost of PV inverters, and it is assumed that the cost ratio of silicon-based IGBT will remain unchanged in the next few years.
Inverter price: In 2021, the materials of Sunshine Power’s PV inverters are basically silicon-based materials, with sales volume of 47GW and business revenue of RMB 9.05 billion, so the price of silicon-based PV inverters is about RMB 0.19/W. According to the inverter price change data of Sunshine Power from 2017 to 2021, the average annual price decreases by about RMB 0.02/W. Therefore, it is expected that the price will gradually decrease in the future. Therefore, it is expected that the price will gradually decrease in the future, assuming that the price will decrease at the rate of 0.02 Yuan/W per year to 0.13 Yuan/W.
Silicon carbide / silicon price ratio: the current price ratio of silicon carbide devices and silicon-based devices is about 4, and in the future it is expected that the cost substitution ratio will be reduced, the proportion of decline should be positively correlated with the price change, so it is assumed that the cost substitution ratio decreases every year.
Substrate cost ratio: The current substrate ratio is 46%, and the ratio is expected to decrease at a rate of 3% per year.
Penetration rate: The penetration rate here refers to the percentage of silicon carbide PV inverters in the total inverters. Referring to CASA data, the penetration rate is 10% in 2021, and is expected to grow at a rate of 10% per year. By 2025, the penetration rate will reach 50%.
Combining the above data and assumptions, the following table shows that the market space will grow at a CAGR of 39% and the demand will grow at a CAGR of 58%. By 2025, the market space will reach 2 billion yuan and the demand for substrates will exceed 500,000 pieces.
Total Market Estimation
According to the Wolfspeed investor report, the share of new energy vehicles + photovoltaic in the total market of silicon carbide is 77% in 2021, and is expected to reach 86% in 2027. Therefore, the market share in this part of the projection is 77% in 2021, and is expected to reach 85% in 2025, based on a 2% annual growth rate. According to the above data, the total market size of global silicon carbide substrate will grow from 1.9 billion yuan to 14.3 billion yuan from 2021 to 2025, and the demand will grow from 300,000 pieces to 4.2 million pieces.
Silicon Carbide Upstream Suppliers
As a leading silicon carbide raw material supplier in China, Henan Superior Abrasives Import & Export Co., Ltd. has steadily supplied high quality black silicon carbide and green silicon carbide to many silicon carbide companies around the world, and our markets cover USA, Canada, Mexico, Peru, Chile, UAE, Saudi Arabia, Russia, Spain, South Africa, Southeast Asia, etc. If you have any demand for silicon carbide micro powder, silicon carbide macro grit, please contact us to get the latest offer of silicon carbide in 2022.
