Among third-generation semiconductor materials, Silicon Carbide (SiC) stands out for its exceptional properties, including a wide bandgap, high breakdown electric field, and excellent thermal conductivity. SiC devices are gradually reshaping the power electronics landscape—from electric vehicles to high-voltage converters—by significantly improving energy efficiency. At the core of these high-performance devices lies a critical fabrication process: SiC Homoepitaxy, which directly impacts device performance, yield, and cost.

What Is Homoepitaxy?

Epitaxy refers to the growth of a high-quality crystalline layer on a substrate, where the layer follows the crystallographic orientation of the underlying material. Homoepitaxy means the epitaxial layer and the substrate are of the same material. In SiC homoepitaxy, this involves growing a SiC epitaxial layer on a SiC substrate, enabling perfect lattice matching and minimizing structural defects.

Why Not Heteroepitaxy?

Compared to heteroepitaxy (e.g., growing GaN on Si), homoepitaxy eliminates lattice mismatch issues that lead to high defect densities and poor interface quality. It allows for low-defect-density, high-reliability device fabrication, which is especially critical in high-voltage and high-power applications.

Key Technologies in SiC Homoepitaxy

1. Chemical Vapor Deposition (CVD)

Currently, CVD is the dominant method for SiC homoepitaxial growth. The process typically uses silane (SiH₄) and propane (C₃H₈) as precursors, introduced into a high-temperature reaction chamber (1600–1700°C) under a hydrogen atmosphere to deposit SiC.
 

2. Epitaxial Thickness and Doping Control

For power devices, the epitaxial layer typically ranges from 5 to 100 μm in thickness and requires excellent thickness and doping uniformity.

Doping type and concentration (n-type or p-type) must be precisely controlled. For instance, nitrogen is commonly used as an n-type dopant, with concentrations ranging from 10¹⁴ to 10¹⁶ cm⁻³.

3. Surface Morphology and Defect Control

A high-quality epitaxial layer must exhibit:

•  Smooth surface morphology (RMS roughness < 1 nm)

•  Extremely low defect density (e.g., threading screw dislocations, basal plane dislocations, and micropipes)

•  Absence of critical defects such as epi-micropipes or carrot defects, which can cause catastrophic device failure

•  Applications and Challenges
 

SiC homoepitaxial layers are widely used in:

•  Schottky Barrier Diodes (SBDs)

•  MOSFET power transistors

•  IGBT-replacement devices
 

The epitaxial layer plays a decisive role in determining on-resistance, breakdown voltage, and thermal stability. However, several challenges remain:

•  High cost: Due to expensive high-purity gases and high-temperature CVD equipment

•  Defect control complexity: Limited by the inherent defect level in the substrate

•  Process consistency: Demands advanced CVD systems to ensure uniform deposition over large-diameter wafers (≥6 inches)

Future Trends

As SiC devices evolve toward higher voltage ratings and automotive-grade reliability, SiC homoepitaxy is advancing in the following directions:

•  High growth rate CVD (>50 μm/h) to boost throughpu

•  Low-temperature growth techniques to reduce thermal stress and energy consumption

•  Large-diameter wafer epitaxy (8-inch sic epi wafer) to improve economies of scale

•  In-situ defect monitoring and intelligent process control for fully automated, optimized production

Conclusion:

As the critical bridge between raw SiC substrates and final power devices, SiC homoepitaxy is emerging as a key metric of competitiveness in the power electronics industry. With continuous advancements in epitaxial technology, SiC is poised to play an increasingly vital role in enabling green energy systems, efficient power conversion, and next-generation smart manufacturing.