Silicon carbide (SiC) is the third generation of semiconductors that has attracted 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 improved greatly. Since then, the industry has accelerated.
In 2001, infineon introduced the first SiC device –300V~600V(16A) SiC schottky diode, then Cree introduced 600V~1200V (20A) SiC schottky diode in 2002, mainly used in switching power supply control and motor control, followed by ST, ROM, fei trillion and Toshiba, etc., have launched the corresponding products. The SiC transistor and the SiC MOSFET were introduced in 2006 and 2011, respectively.
In recent years, as MOSFET technology has begun to be accepted by the market, including psychological threshold and technical threshold, SiC market has begun to grow rapidly. According to the SiC market report released by Yole in 2019, the market size of SiC will be approximately $420 million in 2018, and the agency expects the SiC market to grow at a cagr of 29 percent, which means the market size of SiC will reach $1.93 billion by 2024.
Who are SiC players?
Similar to the manufacturing of integrated circuits, the production of SiC devices also has two modes: IDM and Fabless. At present, the main mode is IDM. SiC industrial chain includes substrate and epitaxial links upstream, devices and modules in mid-stream, and applications downstream. Therefore, there are quite a few players in the SiC industry chain. Among them, Cree of the United States has the largest share. According to Yole’s latest report, Cree accounts for 62% of the entire SiC power device market.
In terms of devices and modules, the strongest technology is still ROM, infineon and Wolfspeed. Domestic manufacturers technology and their gap is still relatively large, domestic or mainly do SiC schottky diode. However, the good news is that the gap is narrowing, and insiders believe that the main reason for the gap is that China started relatively late and has been doing research and development for about 10 years, while foreign companies have been doing research and development for at least 25 years. SiC technology, especially SiC diode technology, is not particularly complicated, as long as the enterprise is willing to do, sink down to do, after a few years can be basically stable, but SiC MOSFET technology is more difficult, to catch up to take a longer time. The SiC diode products of tyco tianrun have been sold in China for many years and have been recognized by the industry.
In terms of OEM, there is no real OEM in SiC industry at present, and it is said that no enterprises with production lines are willing to OEM for others. So Chinese SiC Fabless companies usually go to Taiwanese contract manufacturers, such as hanlei technology. The basic semiconductor in China is a Fabless SiC company.
In recent years, many domestic enterprises have entered the SiC field. In fact, it is not easy to survive in the SiC field. First of all, it is necessary to have enough capital investment, because it is a high investment industry, according to the insiders, not to mention other investment, on a SiC factory utilities, a month is also more than 2 million, so, not enough financial support is difficult to adhere to; The second is the support of the upstream and downstream, whether the upstream can get good materials, whether the device can be sold in the downstream, may need to start their own investment, have a certain control of the market. Third, the technical team is important.
Of course, domestic SiC enterprises have a biggest problem, that is, the upstream materials can not be controlled, there is the problem of incoming goods. Now high-end substrates and epitaxial tablets are basically imported. But if the upstream domestic independent substrate and single crystal manufacturers can make a breakthrough, believe in a few years will be able to improve the situation.
SiC brings engineering challenges
We all know the benefits of SiC are lower impedance, higher operating frequency, and higher operating temperature. For example, the switching frequency of SiC is generally 10KHz~10MHz and is still under development. Its theoretical temperature resistance is more than 400℃, even by the current packaging materials, can easily achieve 225℃.
Of course, higher temperature resistance has advantages, such as the need for water cooling, can make the size of the equipment less. But these features also present other engineering challenges. For example, when SiC devices work at 225℃, how to deal with other peripheral devices, to use devices that can withstand such high temperatures, the cost is a big problem.
Abel Cao, a principal application engineer at CISSOID, has summarized the engineering challenges posed by the application of SiC power devices. There are, in his view, five main challenges.
First, structural design and thermal conductivity design. Traditional technology mainly adopts DCB thermal substrate, Die combination, lead bonding, molding filler or sealing for structural design, most of which are single-side heat dissipation with limited double-side efficiency; The spatial position of Die determines the difference of heat dissipation and parasitic capacitance. These are not suitable for the structure of SiC devices and thermal design, SiC high temperature, the need for new packaging materials and processes.
The other 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 not consistent, the thermal imbalance.
Third, the whole process of simulation and simulation.
Fourth, reliability design and life planning. This includes the required lifetime at the target ambient temperature; High temperature life model; And how to verify the problem, because the current civil does not seem to have 175℃ test standard.
The fifth is the evolution ability of system design. This includes the continuous evolution of new products and product concepts.
SiC power devices with the progress of technology and the improvement of market acceptance, begin to enter the rapid growth, during which there will be many new entrants to the market, also can appear some new applications, hope these new entrants can withstand lonely, can give the whole industry chain can assign, common in this industry, do big, do well.