What Is A Sapphire?
Sapphire is a single crystal form of aluminum oxide (Al₂ O₂), also known as corundum. Unlike polycrystalline alumina ceramics, single crystal sapphire has isotropic (or near-isotropic) optical properties, extremely high surface quality after polishing, and superior chemical resistance.
its comprehensive nature makes it the material of choice for the following applications:
optical window-transmission band from deep ultraviolet (0.14 μm) to mid-infrared (6 μm)
Semiconductor Process Chamber High Temperature Window Surface Plasma Parts-Strong Chemical Resistance Required
wear-resistant parts-hardness close to diamond (Mohs 9)
Main Material Characteristics
applicable scenarios:standard diffusion tube, furnace tube lining, 1150°C below the process boat. Equivalent to Momentive GE-124 / Heraeus F300 / Tosoh ES grades.
| Wavelength | Transmittance (2mm Thick) |
|---|---|
| 193 nm(ArF excimer laser) | ~ 50% (surface loss limit) |
| 248 nm(KrF excimer laser) | ~ 80% |
| 355-1064 nm(Nd:YAG) | > 85% |
| 2.9 μm(CO laser) | > 75% |
| 5.5 μm | > 5 |
Wide transmission window makes sapphire ideal for multi-wavelength process monitoring, pyrometer windows, and UV process windows.
Crystal Orientation Options
| Crystal Orientation | Description | Common Applications |
| C side (0001) | basal plane; z-direction zero birefringence LED | LED substrate, universal window |
| Face A (11-20) | - | Specialty Optics, Substrate |
| R plane (10-12) | - | heteroepitaxial substrate |
| M plane (10-10) | - | Specialty Semiconductor |
| arbitrary/custom available off-axis cutting | can provide off-axis cutting | Customer Designation |
Sapphire processing capacity
Sapphire (Mohs 9) Requires The Use Of Diamond Tools Throughout. Picture Crown Semiconductor Processing Capabilities Are As Follows:
| Process | Up To Specification |
|---|---|
| drilling (cylindrical blank) | diameter ± 0.05mm |
| cutting (diamond wire cutting) | thickness ± 0.02mm, thinnest 0.3mm |
| grinding | flatness <5 μm, parallelism <5 μm |
| optical polishing | Ra < 0.1 nm (angstrom level), face accuracy & lambda;/10 |
| cylindrical/internal grinding | tolerance ± 0.02mm |
| chamfering and edge grinding | helium as per drawing |
Typical Products
Window-flanged or flangeless for process chamber monitoring
Optical Flats and Loodles-UV to Mid-IR Transmission, Polished on One or Both Sides
Laser Window-AR Coated or Die for 193/248/355/1064 nm
wear plates and bearing inserts-take advantage of extreme hardness
custom shaped parts-round, rectangular, prism, bar stock-processed according to drawings
Quality and Documentation
XRD crystal orientation verification (standard accuracy ± 0.5 °)
surface roughness measurement (AFM or profilometer)
Dimensional Inspection Report (CMM)
optical grade parts can provide optical transmittance test report
| Performance Index | Value | Remarks |
|---|---|---|
| crystal structure | hexagonal system (R3, c) | single crystal, Czochralski growth |
| density | 3.98 g/cm³ | - |
| hardness | Mohs Class 9/~ 2000 HV | second only to diamond |
| modulus of elasticity | 335-400 GPa | anisotropy, crystal axis dependent |
| bending strength | 400-690 MPa | - |
| Maximum operating temperature (air) | 1900°C | 1900°C |
| melting point | 2053°C | - |
| thermal conductivity | 23-46 W/(m·K) | is related to the crystal axis |
| Coefficient of thermal expansion | 5.0(a-axis)/ 5.6(c-axis) × 10 over/°C | - |
| refractive index (589 nm) | nₒ = 1.768,nₑ = 1.760 | birefringence |
| optical transmission range | 0.14 - 6.0 μm | UV-VIS-NIR-Mid-IR |
| dielectric constant | 9.3-11.5 | is related to frequency and crystal axis |
| chemical purity | > 99.99% Al₂O₃ | Czochralski Single Crystal Bar |
Sapphire has high transmittance in the wide spectrum of ultraviolet, visible, near-infrared and mid-infrared:
Optical Transmittance
Sapphire is resistant to almost all chemicals at room and high temperatures:
Chemical Resistance
| Chemicals | Tolerance |
|---|---|
| HF (dilute) | room temperature tolerance |
| HF (rich, hot) | above 80°C |
| H₂ SOhis, HNO3, HCl | good tolerance |
| NaOH, KOH (dilute) | well tolerated |
| NaOH, KOH (hot concentration) | prolonged exposure |
| plasma (Cl₂, CF₂, O₂) | good tolerance |
| water, steam | > Excellent tolerance to 1000°C |
We supply and process standard and custom crystal orientation sapphire:
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