Defect Detection in Silicon Carbide Wafer Processing

What is the Role of SiC Substrates in the Silicon Carbide Industry?

SiC substrates are the most crucial component in the silicon carbide industry, accounting for nearly 50% of its value. Without SiC substrates, it is impossible to manufacture SiC devices, making them the essential material foundation.

In recent years, the domestic market has achieved mass production of 6-inch silicon carbide (SiC) substrate products. According to the “China 6-inch SiC Substrate Market Research Report,” by 2023, the sales volume of 6-inch SiC substrates in China has exceeded 1 million units, representing 42% of the global capacity, and is expected to reach approximately 50% by 2026.

Compared to 6-inch silicon carbide, 8-inch silicon carbide has higher performance advantages. Firstly, in terms of material utilization, an 8-inch wafer has an area 1.78 times that of a 6-inch wafer, meaning that with the same raw material consumption, 8-inch wafers can produce more devices, thereby reducing unit costs. Secondly, 8-inch SiC substrates have higher carrier mobility and better conductivity, which help improve the overall performance of devices. Additionally, the mechanical strength and thermal conductivity of 8-inch SiC substrates are superior to 6-inch substrates, enhancing device reliability and heat dissipation capabilities.

How are SiC Epitaxial Layers Significant in the Preparation Process?

The epitaxial process accounts for nearly a quarter of the value in SiC preparation and is an indispensable step in transitioning from materials to SiC device preparation. The preparation of epitaxial layers primarily involves growing a monocrystalline film on the SiC substrate, which is then used to manufacture the required power electronic devices. Currently, the most mainstream method for epitaxial layer manufacturing is chemical vapor deposition (CVD), which utilizes gaseous precursor reactants to form solid films through atomic and molecular chemical reactions. The preparation of 8-inch SiC substrates is technically challenging, and currently, only a limited number of manufacturers worldwide can achieve mass production. In 2023, there are approximately 12 expansion projects related to 8-inch wafers globally, with 8-inch SiC substrates and epitaxial wafers already beginning to ship, and wafer manufacturing capacity gradually accelerating.

How are Defects in Silicon Carbide Substrates Identified and Detected?

Silicon carbide, with its high hardness and strong chemical inertness, presents a series of challenges in the processing of its substrates, including key steps such as slicing, thinning, grinding, polishing, and cleaning. During preparation, issues such as processing loss, frequent damage, and difficulties in efficiency improvement arise, significantly impacting the quality of subsequent epitaxial layers and the performance of devices. Therefore, the identification and detection of defects in silicon carbide substrates are of great importance. Common defects include surface scratches, protrusions, and pits.

How are Defects in Silicon Carbide Epitaxial Wafers Detected?

In the industry chain, silicon carbide epitaxial wafers are positioned between silicon carbide substrates and silicon carbide devices, primarily grown using the chemical vapor deposition method. Due to the unique properties of silicon carbide, the types of defects differ from those in other crystals, including downfall, triangle defects, carrot defects, large triangle defects, and step bunching. These defects can impact the electrical performance of downstream devices, potentially causing premature breakdown and significant leakage currents.

Downfall Defect

Triangle Defect

Carrot Defect

Large Triangle Defect

Step Bunching Defect