As interconnects shrink beyond 90nm node, the presence of etch residues can createhigh via resistance and void nucleation during stress migration (SM) testing. Physical Ar+ preclean is effectivein removing residues, b...As interconnects shrink beyond 90nm node, the presence of etch residues can createhigh via resistance and void nucleation during stress migration (SM) testing. Physical Ar+ preclean is effectivein removing residues, but early SM failures have been seen due to Cu resputter from underlying trenches.Reactive preclean methods show promise in reducing CuOx and cleaning Si, N, F, C,O etch residues inpresence of H+, H* species. In this paper, reactive preclean and PVD PunchThru process (deposit-etch-deposit) is proposed as solution to conventional PVD.The PunchThru process reduces via resistance, improves SM and protects dual-damascene beveland unlanded vias from Cu diffusion by presence of thin Ta deposition step. In addition, the U-shaped interface,which minimizes electron crowding and localized heating effects, increases the mean time to failureby electromigration. Consistent, repeatable blanket film property and good parametric electrical test resultshave proven the production worthiness of this process.展开更多
文摘As interconnects shrink beyond 90nm node, the presence of etch residues can createhigh via resistance and void nucleation during stress migration (SM) testing. Physical Ar+ preclean is effectivein removing residues, but early SM failures have been seen due to Cu resputter from underlying trenches.Reactive preclean methods show promise in reducing CuOx and cleaning Si, N, F, C,O etch residues inpresence of H+, H* species. In this paper, reactive preclean and PVD PunchThru process (deposit-etch-deposit) is proposed as solution to conventional PVD.The PunchThru process reduces via resistance, improves SM and protects dual-damascene beveland unlanded vias from Cu diffusion by presence of thin Ta deposition step. In addition, the U-shaped interface,which minimizes electron crowding and localized heating effects, increases the mean time to failureby electromigration. Consistent, repeatable blanket film property and good parametric electrical test resultshave proven the production worthiness of this process.
