The Role of Silicon Carbide in Power Electronics

Article By : M. Di Paolo Emilio

Silicon Carbide is being adopted in several power applications. The agreement between ROHM and STMicroelectronics will increase its massive adoption in the Industry.

The adoption of energy solutions with SiC materials is accelerating in both the automotive and industrial markets. Making silicon carbide (SiC) wafers is a far more involved process than making silicon wafers, and with demand for SiC devices rising, companies that make them have to nail down sources of SiC wafers.

For example, Rohm and STMicroelectronics recently signed a multi-year agreement under which SiCrystal (part of Rohm Group) will provide over $120 million of 150mm SiC wafers to STMicroelectronics. SiCrystal will supply ST with monocrystalline silicon carbide wafer substrates (figure 1).

Why is this so important? Because the properties of SiC are particularly well-suited for a variety of power components and devices used in electric vehicles, fast charging stations, renewable energy, and various industrial applications.

Figure 1: A silicon carbide wafer [Source: STMicroelectronics.]
Figure 1: A silicon carbide wafer [Source: STMicroelectronics.]

SiC offers a number of advantages in terms of energy, which is why it has been and will be the focus of attention in the development of the new power electronics, together with its cousin GaN.

They are the main wide bandgap (WBD) semiconductor materials. SiC is able to withstand substantially higher voltages, up to ten times higher than typical silicon. This means fewer series components to be used in high-voltage electronics applications, reducing complexity and system costs.

SiC SBDs (Schottky barrier diode) are already replacing silicon in the semiconductor industry. GaN could be a strong competitor in specific markets. Inverters with SBDs have dramatically reduced recovery losses, resulting in improved efficiency. Power design has to keep in mind several requirements, including space and weight, which, together with efficiency, play a significant role.

SiC-SBDs are increasingly applied to power factor correctors (PFC) circuits and secondary side bridge rectifiers in switching mode power supplies. The portfolio of Rohm SiC-SBDs includes 600V and 1,200V modules, with an amperage rating range from 5A to 40A.

The efficiency of conventional power electronics does not exploit the full quality of a semiconductor, with a loss of about 15% of efficiency in the form of heat. Due to its physical properties, the SiC semiconductor material has great potential to meet the requirements of these market trends. Lower losses correspond to lower heat generation, which is reflected in more straightforward, cheaper, smaller, and lighter cooling systems and, therefore, higher power density. Low switching losses allow an increase in switching frequency and a reduction in component size. The reduction in size is more or less proportional to the increase in frequency.

Markus Krämer, head of global sales and marketing at SiCrystal GmbH, said, “Based on the application scenarios of an electric vehicle, various requirements are imposed on the power electronics systems by the automobile manufacturers. These contain, among other things e.g. resistance to temperature changes, vibration resistance, operational reliability at different temperatures as well as a long lifetime.

“In addition,” he continued, “the requirement of high-power density in the integrated systems is already considered self-evident by automobile manufacturers. Furthermore, the entire system costs, as well as the efforts occurring in the product design phase, are to be kept low while at the same time, product quality and operational safety have to be guaranteed as well. All of these points and the fact that we currently recognize a strong demand growth for SiC products in the next years underline that we need to supply customers consequently with a high-quality substrate. This agreement confirms that a well-proven supply chain from the SIC substrate to the components and modules is essential,” Krämer said.

As time goes by, silicon, as we know it, may gradually be eliminated. SiC clearly has many advantages over silicon, but still needs improvements in terms of costs and production processes. The market demands highly efficient devices, with the ability to handle high voltages and currents and capable of operating at much higher temperatures than silicon. The new industry has a strong need for SiC and GaN.

The global silicon carbide market is expected to grow with a CAGR of 15.7% from 2019 to 2025. The increasing use of the product in power electronics, especially in e-mobility, is expected to sustain even more significant growth.

“The market size of SiC is around €408 million in January 2020. We expect a further boost of the market, hence a great contribution to the expansion of SiC. Furthermore, we are convinced that the 8-inch market will accelerate as the SiC market grows,” said Krämer.

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