In the semiconductor industry, 6N and above ultra-high-purity tungsten powder is an irreplaceable critical material. It is both the core raw material for tungsten hexafluoride electronic specialty gas and the upstream source material for tungsten sputtering targets. Its purity, particle size, and oxygen impurity levels directly determine the yield of advanced-process chips. As process nodes advance toward 3-7nm and memory stacking layers continue to increase, the strategic industrial value of ultra-high-purity tungsten powder continues to become more prominent. This article will analyze the technical difficulties in preparing ultra-high-purity tungsten powder and China's core industrial advantages, and introduce its segmented applications and industrial value in core semiconductor scenarios.
Difficulties in Preparing Semiconductor-Grade High-Purity Tungsten Powder
Tungsten concentrate is the source ore for preparing tungsten-based materials, and naturally contains various impurity elements such as molybdenum, iron, potassium, sodium, silicon, phosphorus, arsenic, as well as uranium and thorium. For semiconductor chip manufacturing, these trace impurities can have fatal effects on device performance and yield. For example:
● Molybdenum: If residual in tungsten powder, it will enter the interior of the chip with thin film deposition, causing leakage and device parameter drift, and in severe cases resulting in chip short-circuit failure;
● Alkali metals such as Na and K: Under the action of an electric field, they are prone to ion drift in the gate oxide layer of MOS devices, causing threshold voltage drift and increased leakage current;
● Transition metals such as Fe, Ni, and Cu: They can form deep-level defects in the silicon bandgap, shortening carrier lifetime;
● Non-metallic impurities such as oxygen and carbon: They affect target density or form harmful second phases... Therefore, semiconductor-grade high-purity tungsten powder has stringent purity thresholds, especially for 7nm and 3nm advanced logic chips and high-end storage, requiring 5N (99.999%) or even 6N (99.9999%) ultra-high-purity levels. Molybdenum, alkali metals, and radioactive impurities need to be controlled at the ppm or even ppb level, and gas impurities such as oxygen and carbon also need strict control. Ordinary industrial tungsten concentrate directly smelted completely cannot meet electronic industry standards, and a complete deep purification process must be added. At present, the main purification path for semiconductor-grade high-purity tungsten powder is: tungsten concentrate is first converted into a tungsten salt solution through alkaline decomposition or acid decomposition; then ion exchange and solvent extraction combined processes are used to separate and remove various harmful impurities such as molybdenum, alkali metals, silicon, arsenic, and phosphorus at the molecular level, obtaining a purified high-purity ammonium tungstate solution; after evaporation and crystallization, high-purity APT crystals with a purity of 99.95% and above are obtained; the high-purity APT is then calcined to form tungsten trioxide, and then reduced using ultra-high-purity hydrogen through multi-stage temperature-controlled reduction to finally produce semiconductor-grade high-purity tungsten powder.
Therefore, semiconductor-grade high-purity tungsten powder has stringent purity thresholds, especially for 7nm and 3nm advanced logic chips and high-end storage, requiring 5N (99.999%) or even 6N (99.9999%) ultra-high-purity levels. Molybdenum, alkali metals, and radioactive impurities need to be controlled at the ppm or even ppb level, and gas impurities such as oxygen and carbon also need strict control. Ordinary industrial tungsten concentrate directly smelted completely cannot meet electronic industry standards, and a complete deep purification process must be added. At present, the main purification path for semiconductor-grade high-purity tungsten powder is: tungsten concentrate is first converted into a tungsten salt solution through alkaline decomposition or acid decomposition; then ion exchange and solvent extraction combined processes are used to separate and remove various harmful impurities such as molybdenum, alkali metals, silicon, arsenic, and phosphorus at the molecular level, obtaining a purified high-purity ammonium tungstate solution; after evaporation and crystallization, high-purity APT crystals with a purity of 99.95% and above are obtained; the high-purity APT is then calcined to form tungsten trioxide, and then reduced using ultra-high-purity hydrogen through multi-stage temperature-controlled reduction to finally produce semiconductor-grade high-purity tungsten powder.
However, this process has extremely high technical barriers:
(1) The difficult problem of deep tungsten-molybdenum separation: Tungsten and molybdenum are adjacent elements in the same group, and their ionic radii and aqueous solution chemical behaviors are extremely similar, making it very difficult to completely separate them by conventional precipitation and crystallization methods; (2) Deep removal of alkali metals and trace heavy metals: Potassium and sodium are very easily adsorbed in resin pores and crystal gaps and are difficult to completely wash out. Auxiliary materials can also introduce secondary impurities, requiring multi-stage ion exchange and repeated recrystallization to reduce them to the ppb level. (3) Multi-stage temperature-controlled reduction control: After high-temperature calcination of APT, gentle heating is first required to reduce tungsten trioxide to tungsten dioxide. After that, the temperature is further raised to completely reduce it to pure metallic tungsten powder. Because tungsten powder is extremely sensitive to parameters such as temperature, its process window is very narrow. Slight changes in hydrogen flow rate, furnace gas environment, and temperature curve will affect the particle size and purity of the final tungsten powder. (4) Full-process prevention of secondary contamination: From leaching, extraction, crystallization to calcination and hydrogen reduction, equipment materials, reagent purity, and environmental cleanliness will introduce new impurities, placing extremely high requirements on equipment selection, auxiliary material control, and workshop cleanliness levels. In addition to chemical purity, semiconductor tungsten powder also needs strict control of particle size, particle size distribution, degree of agglomeration, and oxygen and carbon gas impurities. Under the premise of high purity, balancing powder physical indicators and achieving batch-to-batch consistency in mass production is difficult.
Core Advantages of China's Semiconductor-Grade High-Purity Tungsten Powder Industry
Resource end: Global tungsten resources are highly concentrated, and China has a high-quality tungsten ore resource foundation, accounting for 52% of global reserves. In particular, the black tungsten ore in mining areas such as southern Jiangxi has low native molybdenum impurity content and excellent innate raw material conditions, providing high-quality source assurance for semiconductor-grade high-purity APT and high-purity tungsten powder production, reducing the process pressure for deep molybdenum removal from the ore end. Industry end: Relying on a complete tungsten metallurgy industrial system, China has already opened up the full chain of "tungsten ore - APT - high-purity tungsten oxide - 6N high-purity tungsten powder - tungsten hexafluoride / tungsten target." After decades of iteration in hydrometallurgical processes, domestically mature applications have been achieved in sulfide molybdenum removal, multi-stage ion exchange, and solvent extraction deep purification processes, solving the core technical pain points of tungsten-molybdenum separation and trace impurity removal. Among them, China Tungsten and Hightech and Xiamen Tungsten have become the only two companies in the world capable of stably mass-producing high-purity tungsten powder above 6N. In addition, high-purity tungsten powder has high activity and a large specific surface area. After contact with air, it is extremely easy to rapidly oxidize and adsorb moisture and impurities, directly leading to decreased purity and deterioration of powder performance, making it unable to meet semiconductor process use standards. The conventional effective inventory cycle for high-purity semiconductor-grade tungsten powder in the industry is only 3 to 5 months, and storage conditions are extremely harsh. It must be kept vacuum-sealed throughout and stored under a high-purity argon inert atmosphere, combined with dedicated clean storage facilities. Its storage renovation cost and operation and maintenance cost far exceed those of ordinary metal raw materials, and long-term stockpiling is relatively uneconomical. This characteristic further strengthens China's monopoly advantage in the global supply chain.
Applications of High-Purity Tungsten Powder in Core Semiconductor Scenarios
Semiconductor-grade high-purity tungsten powder is the core raw material for two key consumables: tungsten hexafluoride (WF₆) electronic specialty gas and tungsten sputtering targets. It is an indispensable refractory metal material for advanced logic chips and high-end memory chips, and has irreplaceable application value in 3nm/7nm advanced logic chips, 3D NAND flash memory, and HBM high-bandwidth memory. (1) Used to prepare tungsten hexafluoride (WF₆) electronic specialty gas: Using high-purity tungsten powder and high-purity fluorine gas as raw materials, electronic-grade tungsten hexafluoride is obtained through fluorination and multi-stage rectification purification, and is used as a CVD chemical vapor deposition precursor gas. During wafer manufacturing, tungsten hexafluoride decomposes to generate metallic tungsten, which is used to fill the large number of tungsten plug vias inside the chip to achieve vertical interconnection between circuits on different layers; it can also be used for metal barrier layer and word line thin film deposition. With the explosive growth of the AI computing industry, the number of stacking layers in HBM high-bandwidth memory is increasing, and 3D NAND flash memory continues to iterate toward more than 200 layers. The number of vertical vias is multiplying, and demand for tungsten hexafluoride and upstream high-purity tungsten powder is still growing rapidly. (2) Used to prepare semiconductor tungsten sputtering targets: High-purity tungsten powder is formed, sintered, and precision machined to obtain tungsten targets. By relying on the PVD magnetron sputtering process, tungsten metal thin films are deposited on the wafer surface for barrier layers, electrodes, and interconnect films inside logic chips and memory chips. Advanced processes at 7nm and 3nm have stringent requirements for target purity, grain uniformity, and density. The source of the target is high-purity tungsten powder, and powder purity directly determines the quality of the sputtered film. Excessive impurities will bring about a series of problems such as particle defects, leakage, and decreased yield.