Sputtering is the use of ion source generated ions, in the vacuum to accelerate the accumulation of high-speed ion current bombarding solid surface, so that the atoms on the solid surface leave the target material and deposit on the substrate surface, thus forming nano (or micron) film, the solid body bombarded is called the sputtering target material. Sputtering coating is the basic means of preparing functional thin films in the fields of integrated circuits, flat panel displays (including liquid crystal displays and touch screens, etc.), thin film solar cells and light-emitting diodes (LED), etc., and the sputtering target material has become an indispensable basic material in these fields.
Generally, the preparation process used for molybdenum and niobium alloy sputtering target material includes: 1) smelting and casting process: smelting molybdenum and niobium with a certain ratio of raw materials, pouring the alloy melt into the mold to get the ingot, and then making the target material through heat treatment, forging, extrusion and emulsion. The problems of this process are: ingot casting defects, such as shrinkage cavity, shrinkage porosity, inclusion, segregation, etc., and ingot grain size, resulting in reduced coating efficiency and film quality decline, if further processing, low finished product rate, high cost; Because molybdenum and niobium are high melting point metals, vacuum arc melting or vacuum electron beam melting is usually used, which requires high preparation conditions and high cost. It is difficult to obtain uniform molybdenum niobium alloy target material, even if the secondary remelting and other processes, the homogeneity of the separation is difficult to meet the requirements, resulting in a decrease in the composition uniformity of the film.
For the preparation of molybdenum and niobium alloy target material, the commonly used powder metallurgy process includes: (1) After mixing a certain amount of molybdenum powder and niobium powder, the target material of molybdenum and niobium alloy is obtained by pressing forming and vacuum sintering. Because of niobium with oxygen binding force is stronger, and in the process of sintering molybdenum powder oxygen impurity and is absorbed by niobium in the cause from molybdenum powder and niobium powder oxygen impurity in the volatile difficulties, prevent sintering densification, so the process of target material only 80 ~ 89%, relative density porosity is large, flying splash particles produced in the process of sputtering, and significantly reduce the sputtering coating quality. ② A certain amount of molybdenum powder and niobium powder are mixed, and then compressed and formed by vacuum hot pressing or hot isostatic pressing to obtain the target molybdenum and niobium alloy. The relative density of the target material obtained by this process can reach 90~97%, but the carburizing is caused by the use of graphite mold, and the equipment used is complex and expensive. A certain amount of molybdenum and niobium powders were mixed, formed by pressing and sintered, and then the target molybdenum and niobium alloy was obtained by hot isostatic pressing. The relative density of the target material obtained by this process can reach more than 98%, but the process is long, the operation is complicated, and the cost is high. (4) After the sintered billet is made by "process ①", the target material with high density is obtained by forging or milk processing. However, due to the low density of sintered billet, the processing yield is low, and the process is complex, and the preparation cost is high.
