Review—Ruthenium as Diffusion Barrier Layer in Electronic Interconnects: Current Literature with a Focus on Electrochemical Deposition Methods

Ruthenium is one of themost promising candidates to replace tantalum and titanium based diffusion barrier layers inmicroelectronics. Its unique properties allow the deposition of ultrathin layers with controlled thickness by means of a wide variety of different techniques. Ruthenium barriers are characterized by good thermal stability, low resistivity and great adherence. Moreover, the copper filling deposited during the Damascene process can be directly applied on the barrier without the need of a seed layer. As a consequence of the industrial interest in developing new ruthenium based interconnects technologies, a significant literature has been produced in the last few years. The scope of the present work is to collect and analyze the literature on the topic, investigating in this way the technologies developed in the past and the current development stage of ruthenium based barrier layers. Due to their multiple advantages, a special focus is devoted to the manufacturing of ruthenium diffusion limiters by mean of wet electrochemical processes.