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The Technological Secrets of Micro/Nano Tantalum Tubes in Semiconductor Vapor Deposition

In the "atomic-level carving" field of semiconductor chip manufacturing, chemical vapor deposition (CVD) technology places extreme demands on the precision of reactant gas delivery. The micro/nano Tantalum tubes, which undertake this crucial task, directly determine chip yield due to their size limits and process control. Currently, the smallest tantalum tubes used in the semiconductor industry have an inner diameter as low as 50 micrometers and a wall thickness of only 5 micrometers. Such dimensional precision far exceeds that of ordinary metal tubes, supported by a stringent process technology system.

To achieve such tiny dimensions, tantalum tubes must first overcome the "ceiling" of raw material purity. Semiconductor-grade tantalum tubes require a Tantalum purity of 99.998% (4N8) or higher, with the total impurities such as Tungsten, Molybdenum, and Niobium controlled below 0.4 ppm and oxygen content not exceeding 600 ppm. This is because corrosive gases such as tungsten hexafluoride and hydrogen chloride transported during CVD react with impurities in the tube to generate contaminants, directly leading to wafer defects. In comparison, even after precise purification, commonly used stainless steel tubes still contain impurities exceeding 50 ppm, failing to meet semiconductor process requirements. While titanium tubes can achieve 4N purity, they react with fluoride gases at high temperatures, making long-term stable operation impossible. This purity advantage makes tantalum tubes the sole choice for micro/nano gas delivery.

The tube drawing process is the core step in achieving micro/nano dimensions. Tantalum tubes are drawn using a "multi-pass progressive diameter reduction" technique. First, high-purity Tantalum rods are pierced to create a thin tantalum tube with an initial diameter of 2 mm, followed by 12-15 passes of cold drawing. The diameter reduction rate for each pass must be precisely controlled between 8% and 12%; too high a rate will cause the tube to crack, while too low a rate will prevent dimensional breakthroughs. Simultaneous intermediate annealing is also required during the drawing process, eliminating processing stress in a 1000℃ vacuum environment to prevent brittle fracture during subsequent drawing. In comparison, while copper tubes are easy to draw, they exhibit severe "necking" when the diameter is reduced to below 100 micrometers, resulting in extremely poor dimensional uniformity. Nickel alloy tubes, due to their higher hardness, can only be drawn a maximum of 8 times, making it difficult to break through the 150-micrometer minimum diameter. Surface treatment directly determines the micro-nano-scale performance of Tantalum tubes. After drawing, Tantalum tubes undergo electrochemical polishing. In a mixed electrolyte of nitric acid and hydrofluoric acid, the surface roughness is reduced to below Ra0.05 micrometers by controlling the current density at 1.5-2 A/dm². This ultra-smooth surface prevents gas from forming eddies inside the tube, ensuring stable flow. Simultaneously, the polishing process forms a dense Tantalum pentoxide film 2-4 nanometers thick on the tantalum tube surface. This oxide film not only enhances corrosion resistance but also prevents impurity migration. In contrast, the natural oxide film of titanium tubes is only 1-2 nanometers thick and easily detaches under corrosive gases; the oxide film of stainless steel has microporous defects, failing to provide long-term protection.

Dimensional inspection technology is equally indispensable. A laser diameter gauge is used to monitor the inner diameter of the Tantalum tubes in real time, with a measurement accuracy of up to 0.1 micrometers. Ultrasonic testing is used to check the wall thickness uniformity. 30% of each batch of tantalum tubes undergoes high-temperature stability testing; after being held at 400℃ for 24 hours, the dimensional change rate must be controlled within 0.5%. These stringent process requirements make micro/nano tantalum tubes irreplaceable in semiconductor vapor deposition, becoming a key support for chip manufacturing's breakthrough towards smaller process dimensions.

AlloyHit specializes in producing Tantalum Tubes, Tantalum Capillary in various specifications.