Reliability improvement using buried capping layer in advanced interconnects

Dielectric failure mechanisms in advanced Cu/low-k interconnect architecture

“…However, as shown in Figure 4.9(a), the dominant conduction mechanism in the comb structure at electric fields more than 1 MV/cm is found to be Schottky emission since it yields a reasonable k value of 2.29, which is close to the dielectric constant of the low-k dielectric used. The same conduction mechanism for similar interconnect stack material and comb test structure were reported in [53]. At electric fields less than 1 MV/cm, an Ohmic conduction is observed as shown in Figure 4.9 (b).…”

Test Structure Design for Precise Understanding of Cu/Low-k Dielectric Reliability

“…The low-k dielectric is a carbondoped SiO 2 (SiOC) and the diffusion barriers used in the interconnect scheme are 50 nm-thick SiC(N) capping layer and 25 nm-thick Ta liner. Part of the hardmask (USG) deposited on the SiOC low-k dielectric was retained after the chemical-mechanical polishing (CMP) step and remained as a buried capping layer (BCL) because it improves the leakage and breakdown field strength of the interconnects/dielectric system [3]. Voltage ramp (V-ramp) test was conducted at room temperature (20 o C) up to 200 V (6.7 MV/cm) and physical failure analysis performed thereafter.…”

The Analysis of Dielectric Breakdown in Cu/Low-k Interconnect System

“…The interconnect system, shown in Fig. 2 (b), consists of Cu with carbon-doped silicon oxide (SiOC) IMD, a dual hardmask layer of undoped silicate glass (USG) and SiC and Ta diffusion barrier [9]. The breakdown electric field was measured to be greater than 7 MV/cm, as shown in Fig.…”