According to the application, the target material mainly includes semiconductor target material, recording medium target material, display film target material, optical target material, superconducting target material, etc. et al. of Shanghai iron and steel research institute made a detailed classification of target materials, corresponding material types and application fields. Among them, target materials for semiconductor application, target materials for recording medium and target materials for display are three kinds of targets with the largest market scale.
The target materials are cuboid, cube, cylinder and irregular shape. Rectangular, cube and cylindrical targets are solid. In the process of sputtering, the circular permanent magnet builds an annular magnetic field on the surface of the target and forms an etching area on the annular surface equidistant between the axes. Its disadvantage is that the uniformity of film deposition thickness is not easy to control, and the utilization rate of the target is low, which is only 20%~30%. Application both at home and abroad in the rotating hollow circular tube magnetron sputtering target, its advantage is target material can be rotating around a fixed strip magnet components, and 360 ° target surface can be evenly etching, utilization rate is as high as 80%.
At present, the main methods of preparing target materials are casting and powder metallurgy.
Casting process; The alloy raw materials with a certain proportion of ingredients are smelted, then the alloy molten liquid is poured into the mold to form ingots, and finally the target material is made by mechanical processing. Casting is smelting and casting in a vacuum. Common smelting methods include vacuum induction smelting, vacuum arc smelting and vacuum electron bombardment smelting. Its advantages are low impurity content of target material (especially gas impurity content), high density and large size. The disadvantage is that it is difficult to obtain alloy targets with uniform composition by ordinary smelting method for two or more metals with large difference in melting point and density.
Powder metallurgy; Alloy raw materials with a certain proportion of ingredients are smelted, poured into ingots, and then crushed. The powder formed by grinding is formed by isostatic pressing, and then sintered at high temperature, and finally the target material is formed. The advantage of powder metallurgy is that the composition of the target material is uniform. Disadvantages are low density and high impurity content. Common powder metallurgy processes include cold pressing, vacuum hot pressing and hot isostatic pressing.
