Molybdenum target material
In recent years, with the continuous development of technology in solar cells, flat panel displays, semiconductor integrated circuits and other fields, thin films prepared by sputtering deposition have been widely used in these fields because of their high density and good adhesion to the substrate material. Molybdenum metal sputtering film because of its low resistivity, strong thermal stability, good corrosion resistance and good environmental performance, so that this film in the solar cell, flat panel display, semiconductor integrated circuit and other fields of the market prospects.
At present, there are many methods for preparing molybdenum target materials for sputtering coating, such as sintering method, electron beam melting, hot isostatic pressing method, etc., but the above methods have advantages and disadvantages, and can not meet the needs of the practical application of large area coating. The cost of electron beam melting is high, the operation is complicated, the metal grain of the molten molybdenum blank is coarse, the subsequent processing is difficult, and it is difficult to ensure the fine and uniform grain structure of the product target material. The target produced by sintering method has many hole defects and insufficient density, and the target produced by sintering method is prone to particle spatter and other problems during use. Using hot isostatic pressing method can not produce large size of the molybdenum target, according to the relevant data show that the length of the target prepared by this method can not exceed 2m.
During the sputtering process, if the number of inclusions in the target is too much or the distribution is uneven, the particles will often form on the wafer, resulting in uneven sputtering thickness or low sputtering efficiency, which seriously affects the film performance. In addition, the sputtering rate of the film is related to the crystallization result and grain size of the molybdenum target, molybdenum atoms are most easily sputtered along the direction of the most compact hexagonal arrangement of atoms, and the sputtering rate of the fine-size grain molybdenum target is also higher than that of the coarse-grain target. Therefore, improving the sputtering rate and quality of molybdenum target can be achieved by changing the grain structure of the molybdenum target, improving the purity of the molybdenum target and refining the grain.
