Thermal performance of sputtered insoluble Cu(W) films for advanced barrierless metallization

Abstract

The thermal performance of sputtered Cu films with dilute insoluble W (1.3 at.%) on barrierless Si substrates has been studied, using the analyses of focused ion beam, x-ray diffraction, and electrical resistivity measurement. The role of the Cu(W) film as a seed layer has been confirmed based on the thermal performance evaluations in both thermal cycling and isothermal annealing at various temperatures. The electrical resistivity of ∼1.8 µΩ-cm for Cu/Cu(W) film is obtained after thermal annealing at 400°C. Because of the good thermal stability, the Cu(W) seed layer is also considered to act as a diffusion buffer and is stable up to 490°C for the barrierless Si scheme. The results indicate that the Cu/Cu(W) scheme has potential in advanced barrierless metallization applications.