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SiC Substrate

Silicon carbide (SiC) substrates have become essential in advanced semiconductor technologies, offering superior thermal conductivity, high breakdown voltage, and excellent chemical stability. SiC wafers are particularly suitable for high-power and high-frequency devices, making them indispensable in applications ranging from power electronics to radio-frequency (RF) devices. Understanding the different types of SiC substrates and their manufacturing processes can provide insight into their critical role in the semiconductor industry.

From an electrochemical perspective, SiC substrates can be broadly classified into two types: conductive and semi-insulating. These classifications are based on the electrical resistivity of the substrate, which directly affects the type of device that can be fabricated.

● Conductive SiC Substrates: Typically used in the production of Schottky diodes, Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs), and Insulated Gate Bipolar Transistors (IGBTs).

● Semi-insulating SiC Substrates: Used in RF and optoelectronic devices. These substrates offer minimal leakage currents, which is critical for maintaining high performance in RF applications such as amplifiers and switches. Additionally, they are used in the fabrication of photodetectors and laser diodes, where the purity and low defect density of the substrate are key factors.

Manufacturing Process of SiC Substrates

The production of SiC substrates is a complex process that involves several steps, each critical to the final wafer quality. The process includes the preparation of raw materials, crystal growth, and the precision cutting and polishing of the wafers.

1. Raw Material Preparation The primary method for SiC substrate production is the Physical Vapor Transport (PVT) method. This process starts with the synthesis of SiC polycrystalline powder from silicon (Si) and carbon (C) in a 1:1 ratio. The purity and particle size of this powder are crucial, particularly for semi-insulating substrates, where impurity levels must be kept below 0.5 ppm. Any contamination at this stage can significantly affect the crystal growth process.


2. Seed Crystal The seed crystal serves as the foundation for SiC crystal growth. It provides the initial lattice structure for the subsequent crystal layers. The seed crystal is placed either within the reactor or above the raw material to guide the growth of a high-quality SiC crystal. The quality of the seed crystal directly influences the final substrate’s defect density and overall crystal integrity.


3. Crystal Growth The core of SiC substrate production lies in the crystal growth stage. The most common methods for growing SiC crystals include Physical Vapor Transport (PVT), High-Temperature Chemical Vapor Deposition (HTCVD), and Liquid Phase Epitaxy (LPE). PVT remains the most widely used method due to its ability to produce large-diameter SiC crystals with relatively low defect densities. One of the challenges in crystal growth is improving yield rates, which continues to be a focus in SiC substrate production.


4. Crystal Ingot Processing Once the crystal has been grown, it is subjected to precise orientation using X-ray diffraction to ensure that the crystal planes are properly aligned. The ingot is then ground and rounded to remove the seed crystal face and the top dome, ensuring that the ingot is of standard diameter and ready for slicing.


5. Wafer Cutting The SiC crystal ingot is cut into thin wafers using specialized cutting techniques. SiC’s hardness, second only to diamond, makes it a challenging material to cut. The cutting process is time-consuming and prone to causing cracks or defects in the wafers. Common cutting methods include slurry wire cutting, diamond wire multi-wire cutting, and laser irradiation separation.

6. Wafer Grinding and Polishing After cutting, the wafers undergo grinding and polishing to achieve a smooth, atomically flat surface. The surface roughness and thickness uniformity are critical, as they directly impact the subsequent epitaxial growth process. Due to SiC’s hardness, high-strength abrasives such as boron carbide and diamond are used. Polishing materials typically include alumina, cerium oxide, and silicon oxide to achieve the required surface finish.

7 Wafer Cleaning and Inspection The final step in SiC substrate manufacturing is cleaning and inspection. This step removes any residual particles or metal impurities from the previous processing steps. The wafers are then inspected for surface quality, crystalline integrity, and electrical properties such as resistivity. The results of these inspections ensure that the wafers meet the stringent requirements of downstream semiconductor manufacturing processes.


Inspection criteria typically include:

• Crystalline integrity: Micro-pipe density, hexagonal voids, dislocation density, and polytype analysis.

• Crystal orientation: Verification of crystal type.

• Impurities: Bulk impurity content.

• Electrical properties: Resistivity measurements.



Semicorex offers industry-leading SiC substrates with superior material quality and cutting-edge processing techniques. Whether you are seeking conductive substrates for power electronics or semi-insulating substrates for RF applications, Semicorex’s SiC wafers deliver the performance and reliability needed for today’s advanced semiconductor devices.