SAPPHIRE
Sapphire Window & Optical Flat
Single-crystal sapphire windows and optical flats for semiconductor process chambers — UV to mid-IR transmission, Ra < 0.1 nm, extreme plasma and chemical resistance.
Individuelle Abmessungen und Spezifikationen auf Anfrage möglich.
Sapphire Windows & Optical Flats
Sapphire windows are used where fused quartz is inadequate — specifically in plasma-intense environments, high-temperature applications above 1200°C, or where the broader mid-IR transmission range (to 6 μm) is required for pyrometry or spectroscopy.
Material Advantages Over Fused Quartz
| Property | Fused Quartz | Sapphire | Advantage |
|---|---|---|---|
| Hardness | 600 HV | 2000 HV | Sapphire: 3× harder → superior plasma erosion resistance |
| Max temperature | 1200°C | 1900°C | Sapphire: 700°C higher use limit |
| Transmission (> 4 μm) | < 10% | > 50% | Sapphire: mid-IR pyrometry possible |
| Chemical resistance vs. HF | Good | Superior | Sapphire: no attack at room temperature |
| Surface finish | Ra < 0.5 nm | Ra < 0.1 nm | Sapphire: better AFM-level polish |
Standard Window Specifications
Unmounted Sapphire Windows
| Specification | Standard | Precision |
|---|---|---|
| Diameter tolerance | ±0.05 mm | ±0.02 mm |
| Thickness tolerance | ±0.05 mm | ±0.02 mm |
| Surface roughness (both faces) | Ra < 0.5 nm | Ra < 0.1 nm |
| Flatness | λ/4 | λ/10 |
| Parallelism | < 3 arc-min | < 1 arc-min |
| Scratch-dig | 60-40 | 20-10 |
| Crystal orientation accuracy | ±0.5° | ±0.1° (XRD verified) |
| AR coating | Available | Available |
Crystal Orientation Options
| Orientation | Birefringence | Best For |
|---|---|---|
| C-plane (0001) | Zero (z-propagation) | General windows, LED substrates |
| A-plane (11-20) | Max birefringence | Specialized optical applications |
| R-plane (10-12) | Intermediate | Heteroepitaxy substrates |
| M-plane (10-10) | Intermediate | Specialized semiconductor |
| Custom off-axis | Per spec | Customer-specified optical axis |
All orientations are XRD-verified with orientation report issued with shipment.
Optical Transmission Data
| Wavelength | Transmittance (2 mm, uncoated) |
|---|---|
| 193 nm (ArF) | ~50% |
| 248 nm (KrF) | ~80% |
| 355–1064 nm | > 85% |
| 2.94 μm (Er:YAG) | > 75% |
| 5.5 μm | > 50% |
Typical Applications
- Plasma chamber viewports — resist plasma erosion where quartz would fail
- Pyrometry windows — mid-IR transmission enables accurate substrate T measurement
- Laser processing windows — UV/IR transparency + damage threshold higher than quartz
- High-temperature reactor viewports — RTP, epitaxy systems > 1200°C
- Wear-resistant covers — wherever mechanical abrasion would damage quartz
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