Sputtering is one of the main techniques for preparing thin film materials. The accelerated ions are bombarded with the solid surface. The ions exchange momentum with the atoms on the solid surface, causing the atoms on the solid surface to leave the solid and deposit on the substrate surface. This process is called sputtering. The bombarded solid is the source material for deposition of thin films by sputtering, usually called target material. Sputtering is a key process in semiconductor chip manufacturing. The quality of sputtering target plays a crucial role in the quality of sputtering films.
Tantalum (Ta) is an important metal material in industry. It has a series of excellent properties, such as high melting point, good processing performance, corrosion resistance, low vapor pressure and small expansion coefficient, etc. It has important applications in the fields of electronics, chemical industry, aerospace and atomic energy industry. Recently, tantalum has received great attention in semiconductor chip manufacturing. With the great scale development of integrated circuit, in deep sub-micron technology, copper will gradually replace aluminum metallized wiring on the silicon wafer materials, because the tantalum has high conductivity, high heat stability, and to the blocking effect of the atom, tantalum for copper with inert at the same time, between Cu and Ta not form chemical compounds, therefore tantalum as an ideal barrier to prevent the spread of copper. High purity tantalum has become the key structural material in IC manufacturing. At present, the main manufacturing method of diffusion barrier layer is physical vapor deposition (PVD), and sputtering target is the key consumable material used in this process. Therefore, tantalum sputtering target plays an important role in modern IC manufacturing. High purity tantalum target material has been widely used in China. The preparation of tantalum board for target material mainly controls four aspects: purity, grain size, grain uniformity and grain orientation. The higher the purity of target material, small grains, the sputtering target material performance is better. With the increase of grain size, the film deposition rate decreases, and within the required grain size range, the more uniform distribution of grain orientation, the better. The better the grain uniformity is, the more uniform the thickness of the film deposited by the target material will be. Within the appropriate grain size range, the plasma impedance of the target material is low, the film deposition rate is high and the film uniformity is good. Due to the high technical requirements for the preparation of high purity tantalum targets for target materials, it is difficult to produce, especially in the high-end target markets such as electronic devices, semiconductors and plane displays. Currently, there is no mature preparation technology.
