The Application of Nitride Fibers and Nitride Particles in Chemical Deposition: From Source Materials to Functional Films

In advanced materials science and the semiconductor industry, chemical deposition technology, particularly chemical vapor deposition, is a key method for fabricating high-performance thin films. And as a refractory metal, niobium is favored for its excellent corrosion resistance, high melting point, as well as unique superconducting and dielectric properties. To achieve the deposition of niobium films, niobium wire and niobium pellet, as two important source materials, play an indispensable role.

Chemical deposition principle and requirements for source materials
Chemical vapor deposition is a technique that involves introducing gaseous precursors into the reaction chamber, where they undergo chemical reactions on the heated substrate surface and form solid films. The most common method to convert solid metallic niobium into gaseous precursors is the halide transfer method.

This process usually involves the following steps:
The solid niobium source reacts with halogen gases (such as chlorine gas, hydrogen fluoride, or niobium pentachloride vapor) at relatively low temperatures to form volatile niobium halides (such as niobium pentachloride, NbCl₅). The volatile niobium halides are carried by the carrier gas (such as argon) to the high-temperature deposition zone.

At the high-temperature substrate surface, the niobium halides are reduced by hydrogen gas, generating a metallic niobium film and releasing hydrogen fluoride as a by-product. In this precise system, the physical forms of niobium wire and niobium pellet directly determine the efficiency, stability, and final quality of the film.

The application of niobium wire as a source material
Niobium wire has specific advantages in CVD systems due to its high purity, regular geometric shape, and large specific surface area. Direct resistance heating source: This is one of the most classic applications of niobium wire. A single or multiple high-purity niobium wires are directly passed through the deposition area, and heated to incandescence (typically 800°C - 1300°C) by applying an electric current. The hot surface of the niobium wire is both the "source area" where it reacts with halogen gases to form precursors, and also provides an ideal high-temperature substrate for the subsequent decomposition or reduction deposition of niobium compounds. This method has high heating efficiency, intense reactions, and fast film formation rates.

Wrapped Basket Source: A thin niobium wire is wound into a porous basket or coil, with small pieces of niobium or niobium pellets filled inside. The entire basket is heated by induction or direct current. This method combines the regularity of the wire with the high packing density of the particles, increasing the overall surface area and utilization rate of the source material.

Due to its relatively small heat capacity, niobium wire can quickly reach the reaction temperature, enabling rapid control of the deposition process. The high-purity niobium wire itself has extremely low impurity content, which is conducive to the deposition of high-purity niobium films. With correct operation, the filamentous structure can maintain its shape, avoiding blockage of the airflow due to collapse or sintering.
The application of niobium pellets as source materials
Niobium pellets are usually small cylindrical or spherical particles prepared by powder metallurgy. They provide another efficient and flexible source material option for CVD systems.

Filler-type source vessel: This is the most common application method. A large number of highly pure niobium pellets are densely but loosely filled into a high-temperature-resistant source vessel (usually made of tantalum, molybdenum, or ceramics). The source vessel is placed in the source area of the CVD furnace and heated by an external heater (such as a radio frequency induction coil or resistance heater). The numerous voids between the niobium pellets ensure that the reaction gas (such as Cl₂) can fully penetrate and react effectively with the surface of the particles, and the generated precursor vapor can also escape smoothly. Fluidized bed reactor: In more advanced systems, tiny niobium pellets can be used as the bed material of the fluidized bed. The reaction gas introduced from the bottom causes the particles to be in a suspended fluidized state, achieving the maximum contact area between gas and solid and extremely high mass and heat transfer efficiency, making it highly suitable for large-scale continuous production.

A large number of particles provide a total reaction surface area far exceeding that of a single filament, resulting in a high and stable generation rate of the precursor, suitable for long-term deposition. The source boat can be easily filled, with high utilization rate of the source material and good economic performance. The total amount of the source and the reaction kinetics can be precisely controlled by adjusting the particle size and filling volume. The particle stacking structure is not prone to overall deformation at high temperatures.

Fortu Tech supplies niobium wire products 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 can produce and process niobium pellet, niobium foil, niobium Capillary Tube, niobium billet, niobium sheet & plate, niobium rod, niobium tubes.