Investigating the electromigration limits of Cu nano-interconnects using a novel hybrid physics-based model

Abstract

To predict the impact of technological variables such as materials, dimensions, interfaces, and operating conditions on Cu electromigration, in this study a hybrid modeling framework is developed by coupling a global Korhonen-type electromigration modeling module with a cellular automaton-based void dynamics module. The modeling framework is corroborated and benchmarked using experiments on Cu interconnects and is used to predict the impact of scaling on Cu electromigration induced stress evolution. The simulations shed light on the impact of dimensional scaling on stress kinetics, void nucleation, and growth phases, where the nucleation phase is found to become longer than the growth phase and voids are found to grow relatively more rapidly upon nucleation in highly scaled linewidth. In addition, the simulations predict 22% lower median time to failure and a higher variability of time to failure for downstream vs upstream electromigration modes due to the more critical impact of near via voiding in downstream cases. Lending further credence to its predictive merits, the model predicts and explains complex R-shift signatures occurring at high temperature electromigration experiments due to void dynamics.

Electromigration Lifetime of Penta-Twinned Gold Nanowires: Implications for Flexible Electronics

“…This drastic change is also shown by the value of the MTTF, almost 10 times as high at 40 °C. This is qualitatively similar to the behavior of microfabricated interconnects …”

“…This is qualitatively similar to the behavior of microfabricated interconnects. 41 To account for the statistical nature of the data and the fact that 10 data points were measured for each temperature, all variables reported include standard deviation confidence intervals (see the Supporting Information for a discussion of uncertainty analysis).…”

Communication—Exploration of Plasma Oxidized Copper Oxide as a Copper Passivation Layer

“…The EM stress induced atomic flux especially at junctions of grain boundaries, which caused voids formation at the early stage. 43,51 As the stress time is increased, voids grow, merge, and eventually interconnect to cause the breakage of the line. 52 Figure 4a shows that the sample with the thin Cu layer has a longer EM lifetime than that of a thick Cu layer.…”

“…In addition, the mechanical and thermal stresses influence the atomic flux in the interconnect line. 43,51,53 It was reported that the thin film was more resistant to those stresses, i.e., less atomic flux, than the thick film was. 54 Therefore, above theories support the observation that the thin Cu line has a longer lifetime than the thick line has.…”

Recent Progress in Physics-Based Modeling of Electromigration in Integrated Circuit Interconnects

“…There is good fit between lifetime statistics derived from measurement (MTTF EXP = 62,305 s, ∆ EXP = 14,012 s) and simulation (MTTF SIM = 60,344 s, ∆ SIM = 12,613 s). Meanwhile, Houman Zahedmanesh et al investigated the EM limits of Cu nanointerconnects by using a novel hybrid physics-based model [93]. The modeling framework incorporates variations of materials, dimensions, interfaces, and operation conditions.…”