Reactive magnetron sputtering is the sputtering of an elemental target containing one or more elements in the presence of a gas that will react with the target materials to form a compound inside the reactor. One example of reactive magnetron sputtering is adding nitrogen to the reactor while sputtering titanium to form titanium nitride (TiN). Reactive magnetron sputtering for thin film processes has been used in numerous industrial applications. For example, in semiconductor processing, titanium nitride (TiN) has been used as a hardmask for copper dual damascene applications.
The reaction mechanism between the sputtered materials and the reactive gas create unique and complex processing stability problems for reactive magnetron sputtering processes. For example, during target sputtering processes, the reactive gas will react with the target surface, chamber kit surface, and at the substrate to form compounds of the deposited film.
One of the biggest challenges in reactive magnetron titanium nitride (TiN) sputtering is defect control. A periodic pure titanium (Ti) sputtering is often implemented to mitigate the brittleness of the titanium nitride (TiN) films on the process kit as well as to mitigate titanium nitride (TiN) formation on the target surface. Due to the periodic pure titanium (Ti) sputtering, the target surface and process kit surface can become significantly altered after titanium (Ti) sputtering, which will cause a noticeable shifting in process parameters and film properties.
Accordingly, the inventors have provided improved methods and apparatus for processing a substrate.