Suppression of Resistance Increase in Annealed Al/W Interconnects by Capacitively Coupled Plasma Nitridation on W Surface

概要

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The suppression of the resistance increase in annealed Al/chemical vapor deposition (CVD)-W interconnects has been achieved by exposing the W surface to N2 plasma before Al deposition. The N2 plasma was generated in a capacitively coupled parallel-plate reactor. This process forms a thin WNx layer at the interface between the Al and the W layer. The WNx layer prevents Al-W alloy formation during annealing at 450°C. With this N2 plasma treatment, the resistance increase after annealing at 450°C is suppressed to only 10% compared to 140–180% in samples without the N2 plasma treatment. The N/W ratio and the thickness of the WNx layer are about 1.1 and 4 nm, respectively. The WNx layer formed in our experiment is found to be thicker and have a higher N concentration than the WNx layer formed by electron cyclotron resonance (ECR) plasma nitridation. This is probably due to the large self-bias voltage of the N2 plasma generated in a capacitively coupled parallel-plate reactor.
INSTITUTE OF PURE AND APPLIED PHYSICSの論文
1996-02-28