Being Unstoppable, the Application of Silicon Carbide Power Devices in Electric Vehicles
By Dr. Min Lu, SiC Substrate Task Force Leader, Migelab
As we all know, because the main driver of Tesla Model 3 adopts all-silicon carbide modules, it opens the way for the mass application of silicon carbide. So far, Model 3 has sold nearly one million vehicles worldwide, and it has been crowned the world's sales champion model for three consecutive years, which is enough to prove that the application of silicon carbide power devices in electric vehicles has no problems in technology, industry and market.
Compared with silicon devices, the superior performance of silicon carbide modules can increase the car's cruising range by 5-10%, speed up faster, charge faster with more power saving, but the price is also very expensive. It can be said that the bottleneck of the silicon carbide industry is that the price of silicon carbide substrates is too high.
Although in recent years, with the substantial increase in market demand and the development of silicon carbide substrate manufacturing technology to promote the improvement of yield, the price of silicon carbide substrates has been declining year by year. But still very high, the price is about 60 times more than the same size silicon substrate. The silicon carbide substrate accounts for up to 50% of the device cost, which ultimately leads to the high price of silicon carbide devices.
Because the cost of device manufacturing has slightly increased with the increase in material size, large-size materials are the first choice to reduce the cost of devices. Nowadays, 4-6 inches of silicon carbide is the mainstream of the market, and it is estimated that 8 inches will also enter the market in three years. Therefore, the SEMI M55 Standard, Specification for Polished Monocrystalline Silicon Carbide Wafers, is pending publication of its newest version. The core content of the revision is to increase the specification requirements for 8-inch silicon carbide to prepare for the industrialization of 8-inch silicon carbide. SEMI Draft Document 6693, Specification for 4H-SiC Homo-Epitaxial Wafer, and three test methods SEMI Draft Document 6768, Test Method for Micropipe Density of Silicon Carbide Wafer by Laser Reflection, SEMI Draft Document 6767, Test Method for Flatness of Silicon Carbide Wafers by Optical Interference, and SEMI Draft Document 6769, Test Method for Residual Stress of Silicon Carbide Wafers by Photoelastic, are currently under development. These four documents will also cover 8 inches in material size.
Silicon carbide "getting on the car" is not an exclusive technology and application, because there is already a mature technology on the car-the "silicon". So the silicon carbide "getting on the car" will inevitably lead to a strong interception of "silicon". The "territories" of the competition include main inverters, OBC and DC/DC. Of course, the other chips on the car, such as MCU, AI and CMOS image sensors, information, intelligence, and control chips are still in the bag of "silicon", which no one can match.
Although silicon carbide has the above-mentioned superior properties, whether these are hard demands of consumers or pain points of use, which determines whether people are willing to pay for these benefits. This is actually a very sensitive market issue. Let the market solve it. In addition, the automobile industry is a traditional industry, and automobile safety is related to the issue of "life and death". Therefore, the supply chain system has always been rigorous and conservative. Therefore, it is very difficult to enter the qualified supplier list of OEM manufacturers. The threshold of technology, reliability and supply capacity of the company is very high, and the certification cycle is also very long.
Although electric vehicles have the characteristics of their emerging business formats, because they are born out of the traditional automobile industry, the above-mentioned high threshold and long certification cycle characteristics are the same as before.
We often hear that the car regulations AEC-Q101, AQG-324 product certification, and IATF16949 system certification are just the steppingstone to the application of car regulations, that is, the necessary minimum requirements, and the more stringent is customer certification. These certification requirements for devices/modules will inevitably be passed on to the certification and requirements for silicon carbide materials. Although there are no relevant standards and certifications for car-regulated silicon carbide materials, I think it is necessary to carry out research and creation in this area. Because the quality of silicon carbide materials is far from the level of silicon materials, it is necessary to give a standard to select high-reliability materials that meet automotive regulations, so as to promote the application of silicon carbide materials in electric vehicles.
Nowadays, in addition to a Tesla Model that uses silicon carbide, BYD also uses a full silicon carbide module main inverter on BYD Han models. There are probably dozens of car companies that use silicon carbide technology on OBC. However, the penetration rate of silicon carbide in the automotive power device market is only about 5%. Of course, many device manufacturers, such as Wolfspeed, Infineon, Rohm, ON Semiconductor, etc., are cooperating with Tier 1 or automakers. Making full preparations for silicon carbide to "get on the car", because after all, this is a future "big cake" of tens of billions of dollars a year, and no one wants to miss it.
Based on the above reasons, the road of silicon carbide "getting on the car" will be long-lasting, and its market penetration rate depends on the rate of decline in the price of silicon carbide (the core is the decline in the price of silicon carbide substrates), and it is estimated to be around 2030 or 2035. The penetration rate of silicon carbide in the automotive power device market will reach about 50%. Therefore, silicon carbide and silicon will coexist in the car for a long time. After silicon carbide price falls to a certain level, it will enter the middle and low-end car market with the largest car market capacity. A long penetration cycle is actually a good thing. This can give the EV industry more time to grow, and at the same time give the "latecomers" more time and opportunities to catch up with the "first movers", which will facilitate the formation of a relatively healthy and benign market competition.
In the EV race track, who will eventually win, I think the main competitions are as follows:
- Technology is king. King technology is not the most advanced technology, but the best technology to use. Low-cost and high-performance technologies, such as crystal growth technology and packaging technology, especially need breakthroughs. One is an issue related to affordability. The other is related to using well. In this regard, material and device standards must keep up with the pace of technology.
- Management-oriented. Once it enters the OEM supply chain, the demand is considerable. It must be supported by a large, reliable, stable and safe production capacity. Without a strict, advanced and mature management system, I am afraid that it will be difficult to do the job. Therefore, management standards and system certifications such as quality, EHS, energy conservation and emission reduction need to be continuously deepened.
- Cooperation is the soul. The application of vehicle regulations has a high threshold and a long period. The core is that a firm and reliable relationship of trust must be established between supply and demand. Only in this way can we communicate efficiently, solve problems quickly, and iterate efficiently to fabricate safe, reliable and cost-effective electric vehicles. Therefore, it is necessary to establish a silicon carbide substrate and epitaxy-device and module-Tier1-OEM supply chain cooperation alliance at the beginning, carry out in-depth practical cooperation, and gradually establish a complete relationship of mutual trust. Therefore, supply chain management, patent pool sharing in cooperative innovation, and standard-essential patents are all industrial elements that need attention.
In short, silicon carbide power devices "on the car" is unstoppable. Although the journey is far away, it is worth looking forward to!
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June 3, 2021