What Challenges Are Involved in SiC Manufacturing?

SiC is extensively utilized in electric vehicles (EVs) for traction inverters and onboard chargers, as well as in infrastructure applications such as DC fast chargers, solar inverters, energy storage systems, and uninterruptible power supplies (UPS). Despite being used in mass production for over a century—initially as an abrasive material—SiC has also demonstrated exceptional performance in high voltage and high power applications.

From a physical properties perspective, silicon carbide exhibits high thermal conductivity, high saturated electron drift velocity, and a high breakdown electric field (as shown in Figure 1). As a result, systems based on silicon carbide can significantly reduce energy losses and achieve faster switching speeds during operation. Compared to traditional silicon MOSFET and IGBT devices, silicon carbide can deliver these advantages in smaller sizes, offering higher efficiency and superior performance.

Figure 1: Characteristics of Silicon and Wide Bandgap Materials

The operation of silicon carbide can exceed the limits of silicon, with operational frequencies higher than those of silicon IGBTs, and it can also significantly enhance power density.

Figure 2: SiC vs Si

What Opportunities Does Silicon Carbide Present?

For manufacturers, silicon carbide is perceived as a significant competitive advantage. It not only provides opportunities to construct energy-efficient systems but also effectively reduces the overall size, weight, and cost of these systems. This is because systems using silicon carbide are generally more energy-efficient, compact, and durable compared to silicon-based systems, allowing designers to cut costs by reducing the size of passive components. More specifically, due to the lower heat generation of SiC devices, the operating temperature can be maintained below that of traditional solutions, as shown in Figure 3. This enhances system efficiency while also boosting reliability and extending equipment lifespan.

Figure 3: Advantages of Silicon Carbide Applications

In the design and manufacturing phase, the adoption of new chip bonding technologies, such as sintering, can facilitate more effective heat dissipation and ensure connection reliability. Compared to silicon devices, SiC devices can operate at higher voltages and offer faster switching speeds. These advantages enable designers to rethink how to optimize functionality at the system level while enhancing cost competitiveness. Currently, many high-performance devices are using SiC technology, including silicon carbide diodes, MOSFETs, and modules.

Compared to silicon materials, the superior performance of SiC opens up vast prospects for emerging applications. SiC devices are typically designed for voltages not less than 650V, and especially above 1200V, SiC becomes the preferred choice for many applications. Applications such as solar inverters, EV charging stations, and industrial AC to DC conversion are expected to gradually shift towards SiC technology. Another application area is solid-state transformers, where existing copper and magnetic transformers will gradually be replaced by SiC technology, offering higher efficiency and reliability in power transmission and conversion.

What Manufacturing Challenges Does Silicon Carbide Face?

Although silicon carbide holds vast market potential, its manufacturing process also faces several challenges. Initially, the purity of the raw materials—namely SiC granules or powders—must be ensured. Following this, the production of highly consistent SiC ingots (as depicted in Figure 4) requires accumulating experience at every subsequent processing stage to ensure the final product’s reliability (as shown in Figure 5).

A unique challenge of SiC is that it does not possess a liquid phase, meaning it cannot be grown using traditional melt methods. Crystal growth must occur under precisely controlled pressures, making SiC manufacturing more complex than silicon. If stability is maintained in high-temperature and low-pressure environments, SiC will directly decompose into gaseous substances without undergoing a liquid phase.

Due to this characteristic, SiC crystal growth typically employs sublimation or physical vapor transport (PVT) techniques. In this process, SiC powder is placed in a crucible inside a furnace and heated to high temperatures (exceeding 2200°C). As SiC sublimates, it crystallizes on a seed crystal to form a crystal. A crucial part of the PVT growth method is the seed crystal, whose diameter is similar to that of the ingot. Notably, the growth rate of the PVT process is very slow, approximately 0.1 to 0.5 millimeters per hour.

Figure 4: Silicon Carbide Powder, Ingots, and Wafers

Owing to SiC’s extreme hardness compared to silicon, the wafer manufacturing process is also more complex. SiC is an exceptionally hard material, making it challenging to cut even with diamond saws, a hardness that sets it apart from many other semiconductor materials. Although several methods currently exist to slice ingots into wafers, these methods can potentially introduce defects into the single crystal, affecting the final material quality.

Figure 5: Manufacturing Process of Silicon Carbide from Raw Materials to Final Products

Moreover, the large-scale production of SiC also encounters challenges. SiC inherently has more defects compared to silicon. Its doping process is highly complex, and producing large-sized, low-defect SiC wafers implies higher manufacturing and processing costs. Therefore, establishing an efficient and rigorous development process from the start is crucial to ensure the consistent production of high-quality products.

Figure 6: Challenges - Silicon Carbide Wafers and Defects

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