Capacidades
Precision Grinding & Optical Polishing
Multi-stage lapping and optical polishing achieving Ra < 0.1 nm surface finish on fused quartz, sapphire, and precision ceramics for semiconductor and optical applications.
Precision Grinding, Lapping & Optical Polishing
For semiconductor process components and optical elements, surface finish is not merely cosmetic — it directly affects contamination levels, optical transmission, and bonding reliability. Tuguan Semiconductor operates a dedicated multi-stage surface finishing line from coarse grinding through to Ångström-level optical polishing.
Process Stages
Stage 1 · Coarse Grinding
Diamond cup wheels on CNC surface grinders remove stock rapidly while maintaining flatness within 5–10 μm. This stage establishes the gross geometry and removes saw damage from sliced blanks.
| Parameter | Value |
|---|---|
| Material removal rate | 0.1–0.5 mm/pass |
| Surface roughness after | Ra 0.8–1.6 μm |
| Flatness after | 5–10 μm |
| Wheel specification | D46–D107 resin-bond diamond |
Stage 2 · Fine Grinding (Precision Grinding)
Fine-grit diamond wheels (D15–D25) reduce subsurface damage and bring the surface to near-lapping quality.
| Parameter | Value |
|---|---|
| Surface roughness after | Ra 0.2–0.4 μm |
| Flatness after | 2–5 μm |
| Subsurface damage depth | < 2 μm |
Stage 3 · Lapping
Double-side lapping with alumina or diamond slurry achieves the flatness and parallelism required for precision wafer carriers, windows, and substrates.
| Specification | Single-Side | Double-Side |
|---|---|---|
| Flatness | < 2 μm | < 1 μm |
| Parallelism (TTV) | < 3 μm | < 2 μm |
| Surface roughness | Ra 0.05–0.1 μm | Ra 0.05–0.1 μm |
| Max plate size | 500 × 500 mm | Ø 400 mm |
Process control: Slurry concentration, plate pressure, and rotational speed are continuously monitored. All slurries use ultra-pure DI water as carrier fluid to prevent metallic contamination.
Stage 4 · Chemical-Mechanical Polishing (CMP) / Optical Polishing
Final optical-quality polishing uses cerium oxide (CeO₂) or colloidal silica slurry on pitch or polyurethane polishing pads. This stage achieves Ångström-level roughness required for anti-reflection coatings, bonding interfaces, and optical surfaces.
| Specification | Precision Polish | Optical Polish |
|---|---|---|
| Surface roughness | Ra 0.01–0.05 μm | Ra < 0.1 nm |
| Flatness (surface form) | λ/4 | λ/10 |
| Scratch-dig specification | — | 60-40 to 20-10 |
| Subsurface damage | < 0.5 μm | < 0.1 μm |
| Max clear aperture | 500 mm | 300 mm |
Material-Specific Considerations
| Material | Lapping Abrasive | Polishing Slurry | Notes |
|---|---|---|---|
| Fused quartz | Al₂O₃, then diamond | CeO₂ or SiO₂ colloidal | Achieves Ra < 0.5 nm routinely |
| Synthetic fused silica | Diamond | Colloidal SiO₂ | OH content affects polishing rate |
| Sapphire (C-plane) | Diamond (mandatory) | Diamond + Al₂O₃ | Hard axis; slow removal rate |
| Sapphire (A/R-plane) | Diamond | Diamond + CeO₂ | Anisotropic hardness aids polishing |
| Alumina 99.5% | Diamond | Diamond micro-powder | Porous structure limits achievable Ra |
| Silicon nitride | Diamond | Diamond micro-powder | Toughest ceramic to polish optically |
| Boron nitride | SiC or Al₂O₃ | Al₂O₃ or SiO₂ | Soft; risk of smearing at high pressure |
Cleanroom & Contamination Control
All polishing and lapping operations are conducted with:
- Ultra-pure DI water (resistivity > 18 MΩ·cm) as slurry carrier and rinse medium
- Dedicated polishing pads per material — no cross-contamination between quartz, ceramic, and sapphire jobs
- Closed-loop slurry recirculation — filtered to 0.2 μm to remove agglomerates
- ISO Class 7 final rinse and inspection — parts cleaned in ultrasonic tanks and inspected under cleanroom conditions before packaging
Surface Inspection Capabilities
Every polished component is verified using calibrated metrology:
| Instrument | Parameter | Resolution |
|---|---|---|
| White-light interferometer | Flatness, surface form | 0.1 nm vertical |
| Contact profilometer | Ra, Rq | 0.01 nm vertical |
| AFM (atomic force microscope) | Sub-nm roughness | 0.01 nm RMS |
| Nomarski DIC microscope | Scratch-dig, surface defects | Visual standard per MIL-PRF-13830 |
| Calibrated CMM | Dimensional tolerances | ±0.001 mm |
Typical Lead Times for Polished Components
| Work Scope | Lead Time |
|---|---|
| Lapping only (flatness/parallelism) | 3–5 working days |
| Precision polish (Ra 0.01–0.05 μm) | 5–8 working days |
| Full optical polish (Ra < 0.1 nm) | 8–15 working days |
| Large-format (> 200 mm) optical parts | 15–25 working days |