When choosing targets, except the application of the coatings, the following issues should be considered too:
◆ The coating that deposited by targets should have good mechanical strength and chemical stability
◆ The coating that deposited by targets should have good binding force with the substrate. Otherwise, the coating materials with a good binding force to the substrate should be used, and firstly sputtering and depositing a basement membrane and then prepare the desired coatings.
◆ As the coating is formed by reactive sputtering, the coating materials must be easy to react with a gas and generate compound film.
◆ Under the premise of satisfying the coatings performance requirements, the smaller the difference of the thermal expansion coefficient between target and the substrate, the better, so as to reduce the influence of the thermal stress.
◆ The target must meet the technical requirements of purity, impurity content, component uniformity, machining accuracy and so on.