The application of atomic layer deposition for metallization of 65 nm and beyond

With the implementation of Cu interconnect technology, the conventional thin film deposition technique including physical vapor deposition (PVD) shows its fundamental limitation with 65 nm technology node and beyond and the need for introducing metal thin film deposition technique with excellent conformality and controllability of thickness at nanometer scale has been increased. For nanoscale devices, each of the layers or structures used in the interconnect features should be as thin and as perfect as possible. Atomic layer deposition (ALD) has sparked a lot of interest in the interconnect world for a number of reasons. The process is intrinsically atomic in nature, and results in the controlled deposition of films in sub-monolayer units. Ideally, film thickness is determined by number of deposition cycles, rather than timing of a continuous deposition process (like PVD) with a precalibrated deposition rate. Besides application as a diffusion barrier, metal films deposited by ALD is expected to be used in other critical interconnect area including direct platable layer and contact applications. In this presentation, we will present the development of ALD process for various metals and metal nitride layers including Ta, TaN, and Ru focusing on applications for back end of the line process.