IBM and Motorola produced their copper-wired chips by electroplating the copper over the diffusion barrier. Although Monteiro's ion-assisted technique can be used either in conjunction with electroplating or by itself, it has several advantages over electroplating. It can produce thinner, more uniform layers of metals in a variety of architectures. It can be used in narrower trenches with higher depth-to-width aspect ratios. It can fill trenches from the bottom up, automatically eliminating uneven deposition that can lead to voids in the metal lines—or it can produce conformal thin films that mirror the shape of the patterned wafer.