Contact Physics of Capacitive Interconnects

The resistance and capacitance of a typical multipoint contact interface have been used to assess the impact on high-frequency signal integrity. In the past, it has been shown how fully degraded interfaces could still provide acceptable performance for signal transfers at high data rates. In the case of fully degraded contacts, signals were shown to transfer by capacitive coupling and wave propagation. This paper focuses on the critical parameters of a capacitive-coupled interface. Moreover, the physics of the contact interface is related to contacts that rely on capacitive (as opposed to metallic) coupling and electronic tunneling. These results help define the physics and design requirements for capacitive coupling. In addition, critical performance parameters such as real contact area, film thickness, and the nature of dielectric films are defined for high-frequency signal propagation. This paper provides a contrast between the requirements for high-frequency signal transfer using capacitive coupling and electron tunneling versus traditional metallic contact.