April 23, 2024
Silicon Carbide

CVD Silicon Carbide – The Semiconductor Material of the Future

Silicon has been the dominant semiconductor material powering our electronics for decades. However, as devices get smaller, faster and more power efficient, silicon begins to show its limitations. CVD silicon carbide has emerged as a promising alternative that can overcome many of silicon’s shortcomings. With its wide bandgap, high thermal conductivity and high breakdown electric field, silicon carbide offers significant advantages for power electronics, high-temperature devices and other advanced applications.

Silicon carbide, also known as SiC, is a compound semiconductor consisting of silicon and carbon. It exists in over 200 polytypes, but the most common for commercial applications are 3C-SiC and 4H-SiC. CVD or chemical vapor deposition is the main process used for manufacturing high-purity silicon carbide wafers and devices. In the CVD process, gaseous precursors like silane and propane are passed over a silicon carbide seed crystal inside a furnace. The gases decompose and react at the silicon carbide surface, depositing a thin epitaxial layer of semiconductor-quality silicon carbide. Carefully controlling the furnace parameters allows the growth of uniform, high-quality SiC crystals.

Advantages over Silicon
One of CVD Silicon Carbide‘s main advantages over silicon is its wider bandgap of 3eV compared to silicon’s 1.1eV. This means SiC devices can operate at much higher temperatures, voltages and frequencies. SiC allows power transistors and diodes to switch nearly 100 times faster than comparable silicon devices. It also has ten times the critical breakdown electric field strength of silicon. These properties enable smaller, more powerful and more efficient power electronic components and systems. Additionally, CVD silicon carbide exhibits high thermal conductivity of over 3 W/cm-K, almost three times higher than silicon. This allows efficient heat dissipation from densely packed high-power devices.

Applications in Power Electronics
Power electronics is a key application area where silicon carbide offers significant benefits compared to the incumbent silicon technology. Power modules designed with SiC switches and diodes are able to operate at much higher switching frequencies. This directly translates to reduced passive component sizes, lower weight and smaller form factors. By switching faster, power losses are reduced, improving overall conversion efficiency. SiC transistors are enabling next-generation compact, lightweight power converters suitable for electric vehicles, renewable energy systems, telecom equipment, motor drives and other applications where power density and efficiency are crucial. Leading power device manufacturers are rapidly adopting silicon carbide, with SiC MOSFETs and diodes already commercially available. Global production of silicon carbide power modules is to grow exponentially in the coming years.

Future of High-Temperature Electronics
While silicon limits out at around 150°C, silicon carbide devices have been demonstrated to function reliably even above 300°C. This paves the way for high-temperature electronics capable of operating in harsh and hostile environments. Possible applications include downhole oil and gas exploration, automotive under-the-hood systems, high-performance aerospace components, industrial motor drives and more. Recent advances in growing CVD silicon carbide epitaxial layers directly on silicon substrates have further expanded the potential role for SiC. Researchers are exploring integration approaches combining SiC active devices with silicon-based passive components and control circuitry to leverage the best properties of both materials. Continued progress in SiC materials and device fabrication will drive the development of applications beyond the reach of conventional silicon technology.

Despite the obvious advantages, silicon carbide is not without challenges that have slowed its adoption so far. The crystal defects that arise during growth pose difficulties in scaling up substrate diameters and achieving high device yields. Native oxides form less readily than silicon oxide, complicating fabrication steps like oxidation and lithography. Also, the higher raw material and processing costs of CVD silicon carbide still put it at a pricing disadvantage against mature silicon technologies. However, as a specialized niche material, SiC does not need to fully replace silicon. With dedicated efforts to improve crystal quality, expand wafer sizes, refine fabrication processes and lower costs, CVD silicon carbide is positioned for significant penetration in targeted strategic applications where its superior properties translate to clear technical and economic benefits. Looking ahead, silicon carbide promises to open up new frontiers in power management, high-frequency circuits, sensing devices and other domains beyond the limitations of silicon. It represents an important emerging semiconductor for driving further innovation and industrial progress in the decades to come.

1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it