Tantalum capillary tubes: Key engineering materials in CVD/ALD corrosive gas transportation systems

In the fields of semiconductor manufacturing, optical film coating, and advanced material preparation, chemical vapor deposition (CVD) and atomic layer deposition (ALD) are two core technological processes. The stability and yield of these processes are largely dependent on a frequently overlooked but crucial aspect - the delivery pipeline for the reaction precursor gases. Especially in the section downstream of the mass flow controller (MFC) and directly connected to the process chamber, the material selection of this pipeline directly affects the purity of the gas, the repeatability of the process, and the yield of the wafers. When the process involves highly reactive and corrosive precursors such as WF₆, HCl, HBr, Cl₂, F₂, and various metal organic compounds, most conventional metal materials will rapidly corrode, produce particulate contaminants, or form volatile metal halides, resulting in the disruption of the process environment. In such extreme conditions, the tantalum capillary tube, due to its unique physical and chemical properties, has become a widely verified solution in engineering practice. The corrosion resistance of tantalum is attributed to the self-generating dense passivation oxide film (Ta₂O₅) that forms on its surface. When exposed to most corrosive halide gases and reactive precursors, this oxide film exhibits high chemical inertness, effectively preventing further reactions between the underlying metal and the process gases. Unlike stainless steel, nickel-based alloys, or copper alloys - which tend to form volatile metal chlorides or fluorides in halogen atmospheres and thereby contaminate the deposition surface - tantalum maintains a stable passivated state over a wide temperature range and various gas compositions. This property makes tantalum capillary tubes one of the few metal pipeline materials that can be directly used to transport strong corrosive precursor gas flows.

Material purity is an equally important consideration in semiconductor-grade applications. Commercially available high-purity tantalum capillaries can achieve a purity of 4N5 (99.995%) or higher, with extremely low contents of trace impurity elements such as Fe, Cr, Ni, W, Mo, and alkali metals inside. If these impurities are present in the tube wall, they may migrate or volatilize under process conditions and be transported to the wafer surface along the airflow, causing electrical parameter deviations, degradation of the gate oxide layer integrity, or the generation of unexpected catalytic effects. Selecting high-purity tantalum capillaries can eliminate this type of pollution risk at the source. Once such pollution enters the airflow downstream of the MFC, it cannot be removed through filtration or purification methods.

The mechanical properties and vacuum sealing capability of tantalum capillary tubes also make them suitable for high-integrity gas systems. Tantalum has excellent ductility and can be drawn into precise capillary tubes with strict tolerances on inner diameter and wall thickness. This dimensional consistency enables reliable assembly with high-purity compression joints (such as VCR-type interfaces or other metal gasket sealing structures commonly used in ultra-high vacuum systems). A properly installed tantalum capillary tube system can achieve a leakage rate of less than 1×10⁻⁹ mbar·L/s, while ensuring the safety and process integrity of the gas delivery system. The ductility of tantalum also reduces the risk of fracture or work hardening during the installation process, which is a practical advantage compared to other brittle refractory metals.

In processes where it is necessary to prevent the condensation of precursors, the thermal stability of tantalum provides additional protection. Many CVD and ALD precursors have a relatively low saturated vapor pressure, and they are prone to condensation on the cooler tube walls at lower temperatures, resulting in vapor phase component shifts, particle formation, or flow channel blockages. Tantalum capillaries can operate at higher temperatures (typically 150–250°C or higher), with a melting point as high as 3017°C, and will not experience significant creep or oxidation problems within the typical gas pipeline operating temperature range. Under vacuum or inert atmosphere protection conditions, tantalum materials can maintain mechanical strength and dimensional stability over a long period, allowing the downstream end pipes of the MFC to remain stable above the precursor dew point temperature, thereby ensuring that the gaseous components measured by the MFC are consistent with the components actually delivered to the reaction area.

In the actual equipment design and engineering applications, tantalum capillary tubes are mainly found in the following types of scenarios: The most common one is the short pipeline between the MFC outlet and the cavity spray head or injection device, where any contamination in this section will have the most direct impact on the process; Secondly, they are used to transport metal organic precursors in the MOCVD system to grow compound semiconductor materials such as GaN, InGaP, and AlGaN; In the halide processes such as WF₆ tungsten deposition, Cl₂ or HBr plasma or thermal assisted etching, tantalum capillary tubes are also common standard configurations, used to avoid the generation of corrosive by-products. Beyond the mainstream semiconductor manufacturing field, tantalum capillary tubes are also widely used in ALD research equipment, particle accelerator vacuum beam systems, and gas injection systems of magnetic confinement fusion experimental devices. In all these applications, the combination of corrosion resistance, high purity, mechanical reliability, and thermal stability makes tantalum a technically reasonable and in many cases indispensable material choice for engineers when designing hardware for corrosive gas transportation.

Chinese Manufacturer - Fortu Tech supplies Tantalum Capillary Tube to multiple countries and regions around the world. Its service coverage includes the United States, Canada, Russia, Germany, France, the United Kingdom, Italy, Sweden, Austria, the Netherlands, Belgium, Switzerland, Spain, Czech Republic, Poland, Japan, South Korea, as well as Chile, Brazil, Argentina, Colombia and other places in Latin America.

Fortu Tech in China can produce and process Tantalum Capillary Tube, Tantalum billet, Tantalum sheet & plate, Tantalum foil, Tantalum rod, Tantalum wire, Tantalum tubes.

If you have any questions or need quote, price, please send email to info@fortu-tech.com.