Self-consistent design issues for high frequency Cu interconnect reliability incorporating skin effect

This paper presents a self-consistent method to guide high frequency reliability design for a two-level Cu interconnect structure, incorporating the impact of skin effect. A skin-effect-related parameter “Effective Cross Section Area” is introduced to make a more precise prediction of interconnects’ thermal profile due to self-heating. Since via and contact interfaces in Cu interconnects are at the highest risk of failure, via temperature is used to calculate the interconnect stress evolution and lifetime. From the research of the interconnect structure stressed by a type of arbitrary rectangular alternating current, we notice that the direction of the average current must be taken into account, while that consideration is not involved in self-consistent design for Al interconnects. We also found that generally, temperature, current density/intensity, frequency, and duty cycle are four specifications that restrict one another in high frequency interconnect reliability design, and if one increases, interconnects’ tolerance of the other three will decrease.