A quartz boat (also referred to as a quartz wafer boat, quartz wafer carrier, fused quartz boat, or silicon wafer carrier) is a high-purity fused silica carrier used to hold and transport semiconductor wafers during high-temperature thermal processing operations such as diffusion, oxidation, annealing, and chemical vapor deposition (CVD). Made from high-purity fused quartz with SiO₂ content ≥99.99%, these precision carriers maintain structural integrity at elevated temperatures while preventing contamination and ensuring uniform process results across wafer batches.
Product Functions & Applications
Quartz wafer boats are essential components in semiconductor front-end manufacturing. They securely position silicon wafers in precisely machined slots, ensuring consistent spacing and alignment throughout thermal treatment cycles. Key applications include:
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Diffusion & Oxidation Furnaces: Holds wafers during doping and oxide layer growth processes at temperatures up to 1200°C.
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Chemical Vapor Deposition (CVD): Enables uniform thin-film deposition across wafer surfaces in controlled atmospheres.
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Annealing: Supports controlled heating and cooling cycles to activate dopants and reduce crystal defects.
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Wet Cleaning & Etching: Used in RCA clean, SC1/SC2 processes, and acid bath etching (HF, BOE).
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Photovoltaic Cell Manufacturing: Supports silicon wafer diffusion processes in solar cell production lines.
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Laboratory Use: Suitable for sample heating, calcination, ashing, and material research in tube furnaces and muffle furnaces.
These wafer handling carriers are compatible with both horizontal and vertical furnace configurations and are available in clear or opaque quartz depending on thermal or optical requirements.
Material & Specifications
Quartz boats are manufactured from high-purity fused quartz glass, with silicon dioxide (SiO₂) as the primary component. The material is selected for its exceptional thermal stability, low thermal expansion, and superior chemical resistance.
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Material: Fused Quartz (SiO₂ ≥ 99.99%)
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Purity: Up to 99.995% SiO₂ for critical semiconductor applications
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Surface Finish: Acid-polished, Ra ≤ 0.8 μm
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Available Types: Horizontal boats, vertical boats, single-level boats, multi-level boats, slotting boats, and custom-designed configurations
Key Advantages
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High Temperature Resistance: Maintains structural integrity at 1100°C for continuous operation and up to 1300°C for short-term processes.
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Low Thermal Expansion: Coefficient of Thermal Expansion (CTE) of only 0.55×10⁻⁶/°C (20–1000°C), ensuring dimensional stability and minimizing warping during thermal cycling.
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Superior Chemical Resistance: Resists most acids, alkalis, molten salts, and corrosive gases; chemically inert to virtually all elements except hydrofluoric acid (HF).
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Excellent Thermal Shock Resistance: Withstands rapid temperature changes (e.g., 1000°C to room temperature) without cracking.
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Ultra-Low Contamination: High-purity material minimizes ionic impurities (Na⁺, K⁺, Fe³⁺ < 1 ppm), reducing wafer contamination risk during processing.
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High Electrical Insulation: Resistivity up to 7×10⁷ Ω·cm, suitable for processes requiring electrical isolation.
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Long Service Life: Low wear rate and thermal deformation rate < 0.02% at 1200°C under repeated thermal cycles.
Technical Specifications
| Parameter | Specification |
|---|---|
| Material | Fused Quartz (SiO₂ ≥ 99.99%) |
| Maximum Operating Temperature (Continuous) | 1100°C |
| Maximum Temperature (Short-Term) | 1300°C |
| Softening Point | 1730°C |
| Coefficient of Thermal Expansion (CTE) | 0.55 × 10⁻⁶/°C (20–1000°C) |
| Density | 2.2 g/cm³ |
| Tensile Strength | 48.3 MPa |
| Bending Strength | 67 MPa |
| Compressive Strength | > 1100 MPa |
| Hardness | 5.5–6.5 Mohs’ Scale |
| Electrical Resistivity | 7×10⁷ Ω·cm (at 350°C) |
| Surface Finish | Acid-polished, Ra ≤ 0.8 μm |
| Purity Grade | Low metallic impurities (< 1 ppm) |
Standard Wafer Size Compatibility
Quartz boats are available for all major semiconductor wafer diameters and can be customized to specific requirements.
| Wafer Diameter | Slot Capacity | Configuration |
|---|---|---|
| 100mm (4 inch) | 25–50 pcs | Horizontal / Vertical |
| 150mm (6 inch) | 25–100 pcs | Horizontal / Vertical |
| 200mm (8 inch) | 25–150 pcs | Horizontal / Vertical |
| 300mm (12 inch) | Custom | Vertical |
Custom sizes, slot spacing, and boat geometries are available upon request to meet specific furnace requirements.
Quality Assurance & Testing
All quartz boats undergo rigorous quality control procedures to ensure compliance with industry standards:
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Compliance: Meets SEMI F20/F47 standards for semiconductor equipment.
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Impurity Analysis: ICP-MS testing verifies trace metal levels (Na⁺, K⁺, Fe³⁺ < 0.1 ppm).
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Surface Inspection: Surface roughness measurement via AFM ensures Ra ≤ 0.8 μm.
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Thermal Shock Testing: Validated through repeated cycling (1000°C ⇄ 25°C, 10+ cycles).
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Dimensional Verification: Slot parallelism deviation controlled within 0.05mm across slot configurations.
