FUSED QUARTZ
Quartz Diffusion Tube
High-purity fused quartz diffusion and oxidation tubes for semiconductor furnaces — straight bore, flanged, and bell-end configurations for 4" to 12" wafer processes.
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Quartz Diffusion Tubes
Diffusion tubes are the primary reaction chamber in horizontal and vertical furnace systems used for thermal oxidation (SiO₂ growth), dopant diffusion (boron, phosphorus, arsenic), LPCVD thin film deposition, and high-temperature annealing. The tube’s material purity and dimensional accuracy directly affect wafer uniformity and contamination levels.
Product Configurations
Straight-Bore Open Tube
The simplest configuration — a cylindrical tube with both ends open. Used where end caps, flanges, or caps are provided by the furnace OEM.
| Parameter | 4” Process | 6” Process | 8” Process | 12” Process |
|---|---|---|---|---|
| Nominal OD | 125 mm | 175 mm | 225 mm | 325 mm |
| Nominal ID | 118 mm | 168 mm | 218 mm | 318 mm |
| Wall thickness | 3.5 mm | 3.5 mm | 3.5 mm | 3.5 mm |
| Standard length | 1200 mm | 1500 mm | 1500 mm | 1800 mm |
| Max length | 2000 mm | 2000 mm | 2000 mm | 2000 mm |
Flanged Tube
One or both ends fitted with precision-ground flanges for O-ring or metal face-seal connections to furnace end caps.
- Flange OD: Matched to furnace OEM face specification
- Flange face flatness: < 0.05 mm
- Weld integrity: He leak rate < 1×10⁻⁹ mbar·L/s at each weld
- Available flange types: Flat face, raised face, custom
Bell-End Tube
One end formed into a rounded bell — provides an aerodynamically smooth closed end for single-ended loading. Common in vertical furnace designs.
- Bell radius matched to tube OD
- Wall uniformity at bell: ±10% of nominal wall thickness
- Available in all standard OD sizes
Material Grade Selection
| Application | Recommended Grade | Why |
|---|---|---|
| Standard diffusion / oxidation < 1100°C | Grade 1 (Natural) | Cost-effective; < 20 ppm total metals |
| CVD / processes where ppb metals critical | Grade 2 (Synthetic) | < 50 ppb total metals |
| Thermal shield / outer tube | Grade 3 (Opaque) | High IR reflectivity; lower cost |
Quality & Documentation
Every diffusion tube ships with:
- Material certificate — XRF/ICP-OES purity data
- Dimensional inspection report — OD, ID, wall, length, bow
- He leak test certificate (flanged tubes)
- Visual inspection report — bubble, inclusion, surface defect check
Custom Specifications
Drawing-based custom tubes are our specialty. Common custom features include:
- Side ports and gas injection inlets
- Step-bore profiles (different ID at each end)
- Extra-thick wall for high-pressure applications
- Non-standard lengths and diameters
- Opaque outer / transparent inner composite tube