316L Electropolished Coil Tube for Nitrogen Trifluoride (NF₃) Piping Systems
Product Overview
The 316L Electropolished Coil Tube for Nitrogen Trifluoride (NF₃) Piping Systems is a specialized stainless steel coil tube engineered for the safe and reliable transport of Nitrogen Trifluoride — one of the most aggressive oxidizing and corrosive specialty gases used in modern semiconductor manufacturing. NF₃ is widely employed as a chamber cleaning agent in plasma etch systems, thin film deposition reactors, and chemical mechanical planarization (CMP) equipment. Due to its extreme chemical reactivity and potential for catastrophic corrosion of standard stainless steel materials, this coil tube is manufactured to exacting specifications incorporating Electropolished (EP) surface treatment and proprietary passivation processes to ensure long-term chemical resistance and ultra-low particulate contamination.
Designed and produced by Wenzhou Jixing Metal Materials Co., Ltd, this coil tube product (Catalog No. 136) represents a critical component in the gas delivery infrastructure of advanced semiconductor fabrication facilities (fabs), where material integrity directly impacts yield, equipment uptime, and process reliability.
Material & Properties
The base material is ASTM A270 / AMS 5513 Grade 316L Stainless Steel (UNS S31603), selected for its superior resistance to intergranular corrosion, pitting, and stress corrosion cracking (SCC) in highly oxidizing environments. The "L" designation denotes a low-carbon variant (≤0.03% C) that minimizes chromium carbide precipitation during welding, preserving the passive chromium oxide film integrity.
Key Material Characteristics
- Chemical Composition: 16–18% Chromium (Cr), 10–14% Nickel (Ni), 2–3% Molybdenum (Mo), ≤0.03% Carbon (C), ≤0.045% Phosphorus (P), ≤0.030% Sulfur (S)
- Surface Finish: Electropolished (EP) to ≤0.25 μm Ra (Root Mean Square) surface roughness, achieving a mirror-like interior that eliminates micro-cavities where corrosive species could accumulate
- Special Passivation: Post-electropolishing passivation treatment using a proprietary nitric acid–citric acid blend or hydrogen peroxide–nitric acid formulation, followed by ultra-pure water (UPW) rinse to establish a stable, thickened chromium oxide passive layer
- Corrosion Resistance: Significantly enhanced resistance to NF₃ decomposition products including Hydrogen Fluoride (HF), Nitrogen Oxides (NOₓ), and Fluorine radicals
- Particulate Control: Clean manufacturing environment ensuring ≤50 particles ≥0.5 μm per 100 cm² interior surface area
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Base Material | Grade 316L Stainless Steel (UNS S31603) | ASTM A270 / AMS 5513 |
| Surface Treatment | Electropolished (EP) + Special Passivation | SEMI F57 / ASTM A967 |
| Interior Surface Roughness | ≤0.25 μm Ra | SEMI F57 (Mirror Polish) |
| Outer Diameter (OD) | 3.18 mm – 15.88 mm (1/8" – 5/8") | ASME B36.19M |
| Wall Thickness | 0.51 mm – 1.65 mm (0.020" – 0.065") | ASME B36.19M |
| Coil Length | Up to 200 meters (customizable) | — |
| Operating Temperature | −40°C to +150°C | — |
| Operating Pressure | Up to 6.9 MPa (1000 psi) | ASME B31.3 |
| Passivation Method | Proprietary HNO₃/H₂O₂ or Citric Acid Passivation + UPW Rinse | ASTM A967 / SEMI F57 |
| Particulate Level | ≤50 particles ≥0.5 μm / 100 cm² | SEMI F57 |
| End Condition | Clean cut, deburred, end-passivated, protective caps | — |
| Coating | Nylon or PTFE spiral wrap protection | — |
| Certification | CPT (Clean Passivation Test) Verified | SEMI F57 / Customer Spec |
Manufacturing Process
The production of NF₃-grade coil tube follows a rigorous, multi-stage manufacturing protocol designed to eliminate contamination vectors and ensure maximum corrosion resistance:
- Material Sourcing: Vacuum Arc Remelted (VAR) or Electro-Slag Remelted (ESR) 316L bar stock with certified chemistry, low impurity levels, and traceability documentation.
- Forming & Cold Rolling: Precision cold-forming into seamless coil tubing with tight dimensional tolerances (±0.025 mm on OD).
- Heat Treatment & Stress Relief: Solution annealing at 1050°C followed by controlled water quench to restore full austenitic microstructure and eliminate residual stresses.
- Electropolishing (EP): Electrochemical dissolution of the surface layer using a phosphoric acid–sulfuric acid electrolyte bath, removing the contaminated outer layer and achieving ≤0.25 μm Ra surface finish with enhanced surface purity.
- Special Passivation: Application of a proprietary passivation solution to thicken and stabilize the passive chromium oxide film, providing an additional corrosion barrier against NF₃ and its decomposition byproducts.
- Ultra-Pure Water (UPW) Rinse: Final rinse with ≥18.2 MΩ·cm ultra-pure water to remove all chemical residues.
- Clean Packaging: Tube ends capped with PTFE or nylon protective plugs, spiral-wrapped with clean nylon or PTFE tape, and packaged in sealed, clean-room-rated containers.
- CPT Verification: Clean Passivation Test performed per SEMI F57 methodology to validate surface cleanliness, passivation quality, and particulate levels prior to shipment.
Applications
This coil tube is specifically engineered for the semiconductor industry's specialty gas delivery systems, with primary applications including:
- Plasma Etch Chamber Cleaning: NF₃ gas delivery lines for periodic in-situ chamber cleaning in etch tools (e.g., Applied Materials, Lam Research, Tokyo Electron systems)
- Thin Film Deposition Equipment: Gas distribution manifolds and supply lines in CVD (Chemical Vapor Deposition) and ALD (Atomic Layer Deposition) tools
- Photoresist Stripping: NF₃-based photoresist removal systems in lithography areas
- Semiconductor Fab Gas Delivery Infrastructure: Building-level gas manifolds, sub-fab piping, and point-of-use connections for NF₃ supply
- Specialty Gas Mixing Systems: Dilution and blending lines where NF₃ is mixed with carrier gases (N₂, Ar) for controlled delivery
The semiconductor industry's relentless push toward smaller node sizes (≤7 nm) and advanced packaging architectures demands ever-cleaner and more corrosion-resistant gas delivery materials, making this product an essential component in next-generation fabrication facilities.
Quality Certifications & Compliance
- SEMI F57: Certified for semiconductor-grade tubing surface finish, particulate levels, and passivation quality
- ASTM A270: Compliance with standard specification for seamless austenitic stainless steel tubing
- ASTM A967: Standard practice for chemical passivation of stainless steel parts
- AMS 5513: Aerospace Material Specification for 316L cold-worked tubing (where applicable)
- ISO 9001:2015: Quality Management System certification for manufacturing processes
- CPT Verified: Clean Passivation Test documentation provided with each lot, confirming surface integrity and cleanliness
- Material Traceability: Full Mill Test Report (MTR) and heat number traceability for every coil
Unique Selling Points
- Superior Corrosion Resistance: The combination of 316L base material, electropolished surface, and special passivation provides exceptional resistance to NF₃'s aggressive oxidizing and fluorinating chemistry, significantly extending service life compared to standard passivated tubing.
- Ultra-Low Contamination: Mirror-polish EP finish (≤0.25 μm Ra) and clean packaging ensure minimal particulate and metallic ion contamination — critical for maintaining semiconductor process purity.
- CPT Verified Performance: Every coil undergoes independent Clean Passivation Testing, providing customers with documented proof of material quality and readiness for critical semiconductor applications.
- Customizable Dimensions: Available in a wide range of OD and wall thickness configurations to meet specific system design requirements, from sub-fab manifolds to point-of-use connections.
- Full Traceability: Complete documentation package including Mill Test Reports, passivation certificates, CPT results, and material certificates ensures compliance with the most stringent fab qualification protocols.
Note: NF₃ is classified as a strong oxidizer (UN 2939) and poses significant safety hazards. All installations must comply with local regulations, SEMI S2/S8 safety standards, and applicable pressure vessel codes. This coil tube is intended for use in closed, controlled gas delivery systems only.