Comparison of the benefits, from SiO2 to ultralow-K dielectric and air spacing introduction, in term of interconnects performances, for the future high speed Ic’s in a multicoupled lines system

Abstract

Introduction of different low-K to ultra low-K dielectric material in the spacing between neighbour copper interconnects localised on the same level of metallization is analyzed. It is done to evaluate signal integrity such as crosstalk, propagation delay and rise time on a set of several unintentionally coupled Cu lines of micron and nanometer sizes. A full wave analysis based on tangential vector finite element method is implemented in MATLAB environment in order to extract, via a transmission multicoupled line model, the electrically R, L, C, G, Lm, Cm coupled elementary cell. This model with all the mutual impedance and admittance is necessary and more convenient for transient analysis by using commercial software such as Spice or other transient tool. We show that the improvement due to the introduction of low dielectric material can reach more than 200% for the crosstalk and 25% on propagation delay for 1 mm interconnect length. This work also highlights that it is not always realistic to study only a set of two or three lines because some signals appears at the far end of the second or the third interconnect located at the both sides of an attacker.