Silicon carbide (SiC) is the third-generation semiconductor that has received much attention in the past five years. The development of SiC power devices began in the 1970s. By the 1980s, the quality and manufacturing process of SiC crystals had been greatly improved. In the late 1990s, In addition to the United States, Europe and Japan have also begun to invest resources in research and development. Since then, the industry has begun to accelerate development.
By 2001 Infineon introduced the first SiC device, 300V~600V (16A) SiC Schottky diode (SiC SBD), and then Cree introduced 600V~1200V in 2002. (20A) SiC Schottky diodes are mainly used in switching power supply control and motor control, and then ST, Roma, Fairchild and Toshiba have launched corresponding products. SiC transistors (SiC JFETs) and SiC MOSFETs were introduced in 2006 and 2011 respectively.
In recent years, the SiC market has begun to grow rapidly as MOSFET technology has begun to be accepted by the market, including psychological thresholds and technical thresholds. According to the SiC market report released by Yole in 2019, the market size of SiC in 2018 is about 420 million US dollars. The agency expects the SiC market to grow at a compound annual growth rate of 29%, which means that by 2024, the market size of SiC will reach 19.3. One hundred million U.S. dollars.
What are the SiC players?
Similar to the fabrication of integrated circuits, SiC devices are also produced in both IDM and Fabless modes. At present, the main focus is on the IDM model. The SiC industry chain includes upstream substrate and epitaxial links, midstream components and modules, and downstream applications. Therefore, there are actually many players in the SiC industry chain. The largest share of the company is Cree in the United States. According to Yole’s latest report, it accounts for 62% of the entire SiC power device market. It has many years of SiC substrate production experience. Its Wolfspeed is also a vertically integrated production capacity for RF and power devices companies.
In terms of substrates, the domestic Tianke Heda has the longest history, and its products have been sold in the market for more than ten years; the second is Shandong Tianyue, whose technology originated from Shandong University. In addition, Hebei Tongguang, Century Golden Light, Zhongke Energy Saving and Norstel also have related technologies.
In terms of devices and modules, the most powerful technologies are currently foreign manufacturers such as Roma, Infineon and Wolfspeed. The domestic manufacturers’ technology is still quite different from them. The main domestic SiC Schottky diodes are still used. However, the good news is that the gap is narrowing, and insiders believe that the main reason for the gap is that the domestic start is relatively late, and the research and development has been done for about ten years, while the research and development of foreign companies has been done for at least 25 years. SiC technology, especially SiC diode technology, is not particularly complicated. As long as companies are willing to do it, they can do it in a few years, but the technology of SiC MOSFET is more difficult. It takes longer to catch up. time. Like the current Tyco Tianrun SiC diode products have been sold in China for many years, and also received some industry recognition.
In terms of foundries, there is currently no real foundry in the SiC industry. It is said that there are no companies with production lines who are willing to OEM. Therefore, domestic SiC Fabless companies are generally looking for Taiwanese foundries, such as Hanlei Technology. The basic semiconductor in China is a SiC company from Fabless. In recent years, many domestic companies have entered the SiC field. In fact, it is not easy to survive in the SiC field. First of all, there must be sufficient capital investment, because it is a high-input industry. According to industry insiders, not to mention other investments, the cost of water and electricity for a SiC manufacturing plant is more than 2 million a month. Therefore, there is not enough funds. Support is difficult to stick to; secondly, the support situation of upstream and downstream, whether the upstream can get good materials, whether the device can be sold downstream, may need to invest by itself, and have certain control over the market. Third, the technical team is very important.
Engineering challenges brought by SiC
We all know that the benefits of SiC are lower impedance, higher operating frequency and higher operating temperatures. For example, the switching frequency of SiC is generally 10KHz~10MHz, and it is still developing; its theoretical temperature resistance exceeds 400°C, even if it is limited by current packaging materials, it can easily achieve 225°C.
Of course, higher heat resistance is good, for example, without water cooling, the size of the device can be made smaller. But these features actually bring some other engineering challenges. For example, when the SiC device is operated at 225 ° C, how to deal with other peripheral devices, and the device can withstand such high temperature, the cost is a big problem. Abel Cao, chief application engineer from CISSOID, has summed up the challenges that engineering applications pose for SiC power devices. In his opinion, there are mainly five major challenges.
- One is structural design and thermal design. The traditional process mainly adopts DCB heat-conducting substrate, Die combination, wire bonding, molding filler or potting to carry out structural design. Most of these are single-sided heat dissipation, and the efficiency of double-sided is limited; the spatial position of Die determines the difference in heat dissipation. And the difference in parasitic capacitance. These are not suitable for the structure and heat dissipation design of SiC devices. The high temperature of SiC requires new packaging materials and processes.
- The second is stray inductance and distributed capacitance. According to the current topology, there are too many branches, the parasitic inductance is too large, the parasitic inductance of each branch is inconsistent, and the heat is unbalanced.
- The third is full simulation and simulation.
- The fourth is reliability design and life planning. This includes the required lifespan at the target ambient temperature; the high temperature life model; and how to verify the problem, as it seems that there is currently no 175 °C test standard for civilian use.
- The fifth is the evolution of system design. This includes the continued evolution of new products and the continued evolution of product concepts.
As a conslusion, with the advancement of technology and market acceptance, SiC power devices have entered a rapid growth period. During this period, there will be many new entrants participating in this market, and some new applications will appear. I hope these new ones. The entrants can withstand loneliness, empower the entire industrial chain, and work together to make the industry bigger and better.