Impact of via interactions and metal slotting on stress induced voiding

Abstract

Stress induced voiding was investigated for a 0.13 um Cu/lowk interconnect process. The focus of our study was on the "hump" failure mode using a statistical approach to both the design of the vehicle and the data analysis. The TTF was studied with respect to geometrical aspects of the lower metal level, insertion of a dummy via, via arrays and metal slotting for long via chains.

Reliability of Copper Interconnects: Stress-Induced Voids

“…7), for similar reasons as for electromigration; The void size required to cause a fail decreases as the via size. Because stress-induced voids are mainly a problem for wide lines (rather than narrow lines), a simple design solution is to use redundant vias (21)(22)(23).…”

Effect of stress migration on electromigration for nano scale advanced interconnects

“…The possible SM and EM failure mechanisms, design and process integration challenges were also discussed. It was reported that the SM reliability of wide bottom Cu interconnects with the dielectric slot is more superior compared to the standard slot-less Cu test structure [95,96].…”

“…Further studies were carried out by G.D.R. Hall et al, who compared the effect of the dielectric slot for different sizes and locations on the SM robustness [96]. As shown in Fig.…”

“…4.6, it was reported that the metal lead without dielectric slot has the highest failure rate and dielectric slots placed near the via show the lowest failure rate. Moreover, longer slots are proven to be more effective in suppressing stress-induced failure than segmented slots [96]. The control sample with no dielectric slot had the highest failure rate, followed by the segmented slots at the center of the block, long slots at the center of the block and long slots at the edges of the block, near the via [96].…”

“…This method is reported to be able to suppress SM failures [95,96]. The dielectric slot here refers to a redesigned small dielectric block, which is commonly used in wide Cu metal leads to prevent dishing during the CMP process.…”