Asymmetrical Critical Current Density and Its Influence on Electromigration of Two-Level W-Plug Interconnection

Abstract

Electromigration failure at contacts and vias is the potential limitation of interconnect reliability in multilevel structures. In twolevel structures, it has been found that the upper and lower metal levels exhibit different electromigration failure characteristics; the latter fails predominantly. In this work, we have systematically studied the critical current densities of the lower and upper level conductors terminated at W-plug vias. We found that the critical current density for the upper level is significantly higher. The effect of passivation layer on the critical current density is discussed.

Direct observation of void morphology in step-like electromigration resistance behavior and its correlation with critical current density

“…via. 5 The current density is 2 MA/cm 2 , which is significantly higher than the critical current densities for M1 and M2. The critical current densities for M1 and M2, determined from lifetime measurements, are 0.34 and 0.61 MA/cm 2 , respectively.…”

“…The differences in resistance incubation and steady-state resistance increase between M1 and M2 have been discussed. 5 The time period of resistance incubation is shorter in M1; in this case, 20 h for M1 and 40 h for M2. The rate of resistance change in the steady-state regime is greater in M1.…”

“…Detailed data analysis of electromigration lifetime and critical current density has been discussed in a previous work. 5 In this article, we focus on the void morphology and resistance profile. Via chain samples were stressed with constant stripe current densities of 1 and 2 MA/cm 2 at 250°C.…”

Comparative study on the effect of misalignment on bordered and borderless contacts

“…The microstructure of the 0.32 µm stripes is pure bamboo, which is consistent with our previous study. 2 As a comparison, the 0.80 µm voltage monitor line is polycrystalline. In the EM-stressed line, one void is formed near the contact due to electromigration.…”

Microwave evaluation of electromigration susceptibility in advanced interconnects

“…After all, the EM is essentially the displacement of material, carried along with the dense electron current, that leads to the build-up of the mechanical stress and the formation of voids resulting in the degraded device performance. 14 During EM studies on the TSV-enabled samples, the R DC measurably increased only when the voids larger than the TSV’s conductive diameter were formed, forcing the electron flow to go through the resistive barrier shunts. 15 Thus, by the time a measurable resistance change is detected the device under test (DUT) would have been destroyed long ago.…”