High-Purity Alumina Chamber Focus Ring for Plasma Etch & CVD Systems

St.Cera‘s chamber focus ring is a critical process kit component used in plasma etch, CVD, and PVD semiconductor equipment. Manufactured from 99.8% high-purity alumina (Al₂O₃), the ring surrounds the wafer edge to confine plasma and optimize ion angular distribution, thereby improving etch uniformity across the wafer surface. The material offers exceptional plasma resistance, high dielectric strength (15×10⁶ V/m), and thermal stability up to 1600°C, ensuring long-term reliability in aggressive fluorine- or chlorine-based plasma environments. Precision-ground ID/OD and flatness (≤10 μm) enable accurate wafer edge positioning, reducing edge defects and particle generation.

Specifications (based on 99.8% Al₂O₃):

Applications:

• · Dielectric etch chamber focus rings (oxide, nitride etch)
• · Silicon etch chamber edge rings
• · CVD chamber process kit rings
• · PVD chamber shield and clamp rings

Manufacturing Process:

High-purity alumina powder is isostatically pressed → green machined to near-net shape → sintered at 1600°C → CNC diamond grinding of ID, OD, and thickness → lapping to achieve flatness ≤10 μm → ultrasonic cleaning → 100% CMM inspection. Surface finish Ra ≤0.4 μm minimizes particle adhesion.

Quality Control:

• · 100% dimensional inspection (ID, OD, thickness, parallelism)
• · Dye penetrant test for micro-cracks (no cracks allowed)
• · Visual inspection under 20× microscope — no chips, voids, or discoloration
• · Dielectric strength test per ASTM D149 (sampling)

Advantages over Silicon or Quartz Focus Rings:

• · 5–10× longer lifetime in fluorocarbon plasma
• · No consumable erosion particles to contaminate wafers
• · Higher dielectric strength prevents arcing
• · Maintains flatness and dimensional accuracy over thousands of RF hours

Alternative Material — Yttria-Stabilized Zirconia (ZrO₂):

For applications requiring higher fracture toughness (e.g., chambers with frequent thermal cycling or mechanical shock), ZrO₂ focus rings (density 6.03 g/cm³, flexural strength 1000 MPa, fracture toughness 5–8 MPa·m¹/²) are available. However, alumina offers better cost-effectiveness and is the industry standard for most focus ring applications.

Customization:

• · Step profiles, counterbores, or mounting holes per customer drawing
• · Y₂O₃ coating for enhanced plasma erosion resistance (thickness 20–100 μm)
• · Laser marking of part number, date code, or alignment marks

Note: All data strictly follows the supplied Al₂O₃ property table. For ZrO₂ specifications, refer to the supplied zirconia datasheet. Focus ring designs may require patent clearance — customers are responsible for verifying intellectual property rights.