Research on High-Voltage Insulating Materials for Electrostatic Chucks

Core Requirements for High-Voltage Insulating Materials
Electrical Properties 
High Dielectric Strength: Insulation layers must withstand 1.5–5 kV/mm high-voltage fields to prevent breakdown. For example, aluminum nitride (AlN) ceramics offer dielectric strength >15 kV/mm, compatible with sub-3 nm advanced processes. 
Controlled Dielectric Constant: The dielectric constant (ε) directly affects adsorption force (formula: F ∝ εV²/d²). Optimizing ε within 9–12 balances adsorption and insulation safety. 
Low Leakage Current: Leakage current must be <10⁻⁸ A to avoid wafer charge disturbances and process deviations. 
Thermal Management Performance 
High Thermal Conductivity: Materials require >150 W/m·K (e.g., AlN reaches 230 W/m·K). Backside helium cooling achieves ±0.5°C temperature uniformity. 
Low Thermal Expansion Coefficient: Must match silicon wafers (2.6 ppm/℃) to prevent cracking (e.g., AlN: 4.5 ppm/℃). 
Mechanical and Surface Properties 
Plasma Corrosion Resistance: Materials must endure reactive plasmas (e.g., CF₄/O₂) during etching/deposition, with surface roughness <0.05 μm to minimize particle contamination. 
High Hardness and Wear Resistance: Surface hardness >HRA 90 and lifespan >500,000 cycles ensure long-term stability. 
Evolution of Material Systems and Technical Challenges
Ceramic Material Generations: 
Gen 1: Alumina (Al₂O₃) 
  Purity >99.6%, low cost, but thermal conductivity only 30 W/m·K, limited to 8-inch wafers. 
Gen 2: Aluminum Nitride (AlN) 
  Thermal conductivity >180 W/m·K, but sintering is challenging (shrinkage tolerance ±0.05%). Y₂O₃/CaO additives promote densification. 
Gen 3: Composite Gradient Materials 
SiC/AlN structures: Plasma corrosion resistance tripled; 
Nanodiamond coatings: Friction coefficient <0.1, combining heat dissipation and wear resistance. 
Key Challenges in Design and Manufacturing
Dielectric Layer Thickness Control 
   Thickness (d) must balance between 0.3–1.2 mm: too thin risks breakdown, too thick reduces adsorption (F ∝ 1/d²). For 12-inch chucks, flatness <1 μm requires laser-assisted precision machining. 
Bonding Layer Optimization 
Silicone resin layers: Thickness 50–300 μm, thermal conductivity >0.5 W/m·K, temperature resistance >300°C; 
Filler modification: Adding AlN@SiO₂ core-shell particles (1–10 μm) enhances thermal conductivity. 
Surface Microstructure Design 
   Protrusion + microporous structure: 
Protrusion height: 10–50 μm, supporting wafers while reducing contact area; 
Microporous arrays: Inject helium for uniform heat dissipation. 
Future Development Trends
Intelligent Integration 
Embedded Sensors: Temperature/plasma diagnostic sensors enable real-time process feedback. 
Zoned Temperature Control: >100 independent zones, edge temperature variation <0.3°C within 3 mm. 
New Material Systems 
2D Boron Nitride (BN): In-plane thermal conductivity >400 W/m·K, potentially solving high-temperature stress; 
Self-Healing Coatings: Autonomously repair microcracks to extend service life. 
Conclusion
High-voltage insulating materials are pivotal for electrostatic chuck performance, requiring co-optimization of electrical, thermal, and mechanical properties to meet semiconductor process extremes. Future breakthroughs in composite materials and intelligent systems will drive localization of high-performance insulators, supporting sub-5 nm autonomous manufacturing.