Substrate temperature dependence of electrical and structural properties of Ru films

Microstructures and resistivities of sputtered Ru films were investigated as a function of substrate temperature to obtain a single-layered Ru barrier without a Ta/TaN under layer. High resistivity Ru films with a high density of crevices, which enhances Cu diffusion along the crevices, were formed by the conventional sputtering process, i.e., sputtering at room temperature and annealing at 400 degrees C-700 degrees C for 30 min in Ar + 3%H-2. But, crevice-free and smooth Ru films with low resistivity, the same as that for the bulk phase, were formed when substrate temperature add sputtering was raised to 700 degrees C. Ru films formed by this process had (002) preferred orientation and then Cu (111) was formed by plating. This result corresponded to the tendency predicted by ab initio calculations. (C) 2011 Elsevier B.V. All rights reserved.