First: formation of metal compounds on the target

Where is the compound formed during the formation of the compound by the reactive sputtering process from the metal target surface? As the active reactive gas particles collide with the target surface atoms to generate a chemical reaction to form compound atoms, usually an exothermic reaction occurs, and the heat generated by the reaction must be conducted out. Otherwise, the chemical reaction cannot proceed. It is impossible to conduct heat conduction between gases under vacuum conditions. Therefore, the chemical reaction must be performed on a solid surface. The reactive sputter products are performed on the target surface, substrate surface, and other structured surfaces.

Second: Influencing factors of target poisoning

The factors that affect the target poisoning are mainly the ratio of the reaction gas and the sputter gas. Excessive reaction gas will cause target poisoning. During the reactive sputtering process, a process in which the surface of the target surface is covered by the reaction product in the sputtering channel area or the reaction product is peeled off to re-expose the metal surface. If the rate of formation of the compound is greater than the rate at which the compound is stripped, the area covered by the compound increases. At a certain power, the amount of reactant gas involved in the formation of compounds increases, and the rate of compound formation increases. If the amount of reactant gas increases excessively, the area covered by the compound increases. If the flow of the reactant gas cannot be adjusted in time, the rate of increase of the compound coverage area cannot be suppressed, and the sputtering channel will be further covered by the compound when the sputtering target is completely covered by the compound. When the target is completely poisoned, a layer of chemical metal film is deposited on the target surface. Make it hard to be reacted again.

Third: Target poisoning

(1) Positive ion accumulation: When the target is poisoned, an insulating film is formed on the target surface, and when the positive ions reach the cathode target surface, they cannot be directly entered into the cathode target surface due to the barrier of the insulating layer, but are accumulated on the target surface, and the cold field is easily generated. Arc discharge - arcing so that cathode sputtering cannot proceed.

(2) Anode disappears: When the target is poisoned, an insulating film is also deposited on the wall of the grounded vacuum chamber. Electrons that reach the anode cannot enter the anode and disappear.

Fourth: Physical Interpretation of Target Poisoning

Under normal circumstances, the secondary electron emission coefficient of the metal compound is higher than that of the metal. After the target poisoning, the surface of the target is a metal compound. After the ion bombardment, the number of secondary electrons released increases, and the space conduction capacity is improved. .