With the rapid rise of electric vehicles, photovoltaic power, fast charging, and industrial power electronics, silicon carbide (SiC) substrates have become a global hotspot in the semiconductor industry. Among them, the 6-inch 4H-N type SiC substrate is currently the core material for power device manufacturing. A common question is: will it eventually be replaced by more advanced technologies or materials? This article explores the topic from the perspectives of current technology, future trends, and market outlook.

1. Current Technological Landscape

Among the various polytypes of silicon carbide, 4H-SiC has become the preferred choice for power semiconductors due to its outstanding properties:

Wide bandgap (3.26 eV), enabling high breakdown voltage;

High thermal conductivity, ensuring excellent heat dissipation;

High saturation drift velocity, leading to faster switching performance.

In terms of conductivity type, N-type (nitrogen-doped) substrates dominate the industry and are widely used in MOSFETs, Schottky diodes, and related devices. Meanwhile, the 6-inch wafer size has become the commercial and mass-production standard. Major players such as Wolfspeed, ROHM, Sanan Optoelectronics, and TankeBlue have all achieved volume production.

2. Future Development Trends

Although the 6-inch 4H-N substrate currently leads the market, semiconductor materials continuously evolve with new generations of technology.

1. The Rise of 8 inch SiC

Global leaders are actively pushing the 8-inch SiC substrate:

Wolfspeed has built the world’s first 8-inch SiC fab in Mohawk Valley, USA;

ST, Sanan, and ROHM are also accelerating their 8-inch projects.

However, yield rates, defect density, and cost control remain major challenges. It is expected that 2026–2028 will mark the beginning of scaled adoption, but 8-inch will not fully replace 6-inch in the short term.

2. Other Potential Alternatives

GaN (Gallium Nitride): Excellent for high-frequency, low-voltage (<650V) applications, but less suitable for EV traction inverters (>1200V).

Diamond substrates: Theoretically superior but far from industrialization, currently limited to laboratory research.

GaN-on-Si / GaN-on-SiC: Offer low-cost alternatives for some applications, but cannot directly challenge SiC in high-voltage power devices.

3. Market Outlook and Conclusion

Short term (3–5 years): The 6-inch 4H-N type SiC will remain the backbone of power semiconductors, driven by EVs, charging infrastructure, and solar inverters.

Mid-term (5–10 years): 8-inch SiC will gradually expand production and take share in high-end markets, but 6-inch will coexist, especially among mid-sized suppliers and mid-range applications.

Long term (10+ years): Emerging materials such as diamond and other ultra-wide-bandgap semiconductors may come into play, but large-scale substitution is unlikely in the near future.

Conclusion

6-inch 4H-N type SiC substrates will not be replaced in the short term and will continue to be a cornerstone of the power semiconductor industry for years to come. For industry players, this is still the best time to deepen presence in the 6-inch market. At the same time, forward-looking investment in 8-inch SiC and next-generation materials will be critical to maintaining long-term competitiveness.