SiC Epitaxial Wafer Overview

4-inch (100 mm) SiC Epitaxial Wafers continue to play a vital role in the semiconductor market, serving as a highly mature and reliable platform for power electronics and RF device manufacturers worldwide. The 4” wafer size strikes an excellent balance between performance, availability, and cost-effectiveness—making it the industry’s mainstream choice for mid-to-high volume production.

SiC epitaxial wafers consist of a thin, precisely controlled layer of silicon carbide deposited on a high-quality monocrystalline SiC substrate. The epitaxial layer is engineered for uniform doping, excellent crystalline quality, and ultra-smooth surface finish. With a wide bandgap (3.2 eV), high critical electric field (~3 MV/cm), and high thermal conductivity, 4” SiC epitaxial wafers enable devices that outperform silicon in high-voltage, high-frequency, and high-temperature applications.

Many industries—ranging from electric vehicles to solar energy and industrial drives—continue to rely on 4” SiC epitaxial wafers to manufacture efficient, robust, and compact power electronics.

Manufacturing Principle

The production of 4” SiC epitaxial wafers involves a highly controlled Chemical Vapor Deposition (CVD) process:

1. Substrate Preparation
   High-purity 4” 4H-SiC or 6H-SiC substrates undergo advanced chemical-mechanical polishing (CMP) to create atomically smooth surfaces, minimizing defects during epitaxial growth.

2. Epitaxial Layer Growth
   In CVD reactors, gases such as silane (SiH₄) and propane (C₃H₈) are introduced at high temperatures (~1600–1700 °C). These gases decompose and deposit on the substrate, forming a new crystalline SiC layer.

3. Controlled Doping
   Dopants like nitrogen (n-type) or aluminum (p-type) are carefully introduced to tune electrical properties such as resistivity and carrier concentration.

4. Precision Monitoring
   Real-time monitoring ensures tight control of thickness uniformity and doping profiles across the entire 4” wafer.

5. Post-Processing Quality Control
   Finished wafers undergo rigorous testing:

   • Atomic Force Microscopy (AFM) for surface roughness

   • Raman spectroscopy for stress and defects

   • X-ray diffraction (XRD) for crystallographic quality

   • Photoluminescence for defect mapping

   • Bow/warp measurements

Specifications

Applications

4” SiC epitaxial wafers enable mass production of reliable power devices in sectors including:

• Electric Vehicles (EVs)
  Traction inverters, onboard chargers, and DC/DC converters.

• Renewable Energy
  Solar string inverters, wind power converters.

• Industrial Drives
  Efficient motor drives, servo systems.

• 5G / RF Infrastructure
  Power amplifiers and RF switches.

• Consumer Electronics
  Compact, high-efficiency power supplies.

Frequently Asked Questions (FAQ)

1. Why choose SiC epitaxial wafers over silicon?
SiC offers higher voltage and temperature tolerance, enabling smaller, faster, and more efficient devices.

2. What is the most common SiC polytype?
4H-SiC is the preferred choice for most high-power and RF applications due to its wide bandgap and high electron mobility.

3. Can the doping profile be customized?
Yes, doping level, thickness, and resistivity can be fully tailored to application needs.

4. Typical lead time?
Standard lead time is 4–8 weeks, depending on wafer size and order volume.

5. What quality checks are performed?
Comprehensive testing including AFM, XRD, defect mapping, carrier concentration analysis.

6. Are these wafers compatible with silicon fab equipment?
Mostly yes; minor adjustments are needed due to different material hardness and thermal properties.

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