Cantilever beam micro-contacts in a multi-chip interconnection system

In order to examine the use of a compliant cantilever beam structure as a contact scheme for a multichip interconnection system (MIS), multilayer (metals and SiO₂) cantilever beams were fabricated utilizing standard IC processing technologies and micromachining of silicon. The mechanical behavior and electrical characteristics of the beams were investigated to establish their optimum dimensions for use in the MIS. The number of inputs/outputs which can be achieved by this structure is ~1000 per 1-cm² chip site. Au-to-Au contact resistance measurements, as a function of applied force, were carried out employing the Nanoindenter. The contact resistance data and the results from calculations on the maximum deflection and resisting force of these beams suggest that, through proper design, it is possible to achieve simultaneously acceptable and stable resistance values (< ~0.32 Ω) for signal transmission and reasonable flexibilities of beams. Computer simulation results show that the parasitics associated with a typical beam structure are very small (L~20 pH, C~20 fF) compared to conventional packaging technologies