Silicon Carbide (SiC) wafer polishing is a critical process in the production of high-performance electronic devices, particularly for power electronics used in electric vehicles (EVs), 5G infrastructure, industrial drives, and renewable energy systems. As demand for energy-efficient, high-voltage, and high-temperature applications grows, so does the need for ultra-flat, defect-free SiC wafers. This article delves into the SiC wafer polishing process, its importance, methods, market dynamics, and emerging trends.

What is SiC Wafer Polishing?

SiC wafer polishing refers to the mechanical and/or chemical processes used to achieve an ultra-smooth and defect-free surface on silicon carbide wafers. SiC is a hard and brittle wide-bandgap semiconductor, making it ideal for high-power and high-frequency applications—but also making it difficult to process using conventional semiconductor techniques.

The polishing stage is typically one of the final steps in wafer manufacturing, ensuring the surface is suitable for epitaxial growth or device fabrication.

Why Polishing Matters for SiC Wafers

• Surface Quality: Reduces surface roughness (Ra < 1 nm) for better device performance and reliability.

• Defect Elimination: Removes scratches, subsurface damage, and particles from earlier processes like grinding and lapping.

• Yield Improvement: Enhances yield in downstream processes such as epitaxy and photolithography.

• Device Efficiency: Ensures optimal thermal and electrical conductivity.

Key SiC Polishing Techniques

1. Mechanical Polishing (MP)

   • Involves abrasive slurries and pads to remove surface material.

   • Fast but can cause subsurface damage if not controlled.

2. Chemical Mechanical Polishing (CMP)

   • Combines chemical etching and mechanical abrasion.

   • Uses alkaline or acidic slurries with oxidizers (e.g., H₂O₂) to achieve both material removal and smoothness.

   • Preferred for final surface finishing due to high planarity and minimal damage.

3. Plasma-Assisted Polishing (PAP)

   • Uses atmospheric-pressure plasma jets to soften the surface before mechanical removal.

   • Achieves ultra-smooth surfaces (<0.1 nm RMS) with lower forces.

4. UV-Light Assisted Polishing

   • Employs UV-activated chemical reactions to enhance the material removal rate (MRR).

5. Hybrid Polishing

   • Combines various techniques (e.g., MP + CMP + PAP) to optimize performance and cost-effectiveness.

Challenges in SiC Wafer Polishing

• High Hardness: SiC ranks 9.25 on the Mohs hardness scale, requiring robust abrasives like diamond.

• Chemical Inertness: Limits the effectiveness of conventional chemical etchants.

• Subsurface Damage: Needs to be carefully controlled to avoid device failure.

• Cost and Time: Polishing contributes significantly to the overall wafer production cost.

Applications of Polished SiC Wafers

• Power Semiconductors: MOSFETs, Schottky diodes, and IGBTs used in automotive, industrial, and energy sectors.

• RF Devices: Supporting high-frequency applications in 5G and radar systems.

• Optoelectronics: Including LEDs and photodetectors.

• Aerospace and Defense: High-temperature and high-radiation environments.

Market Dynamics and Outlook

Market Growth Drivers

• Growing adoption of SiC devices in EVs and hybrid vehicles.

• Demand from renewable energy inverters, smart grids, and charging stations.

• Push for miniaturization and thermal efficiency in consumer and industrial electronics.

Key Players in the SiC Wafer Polishing Space

• Cree/Wolfspeed

• II-VI Incorporated

• Showa Denko

• Rohm Semiconductor

• Entegris

• Disco Corporation

• Logitech Ltd

Emerging Trends

• Transition to 8-inch SiC wafers to increase chip output per wafer.

• Automation and AI integration for process control and yield enhancement.

• Eco-friendly slurries and consumables to reduce environmental impact.

Read More