Method for forming a multilayered aluminum-comprising structure on a substrate

Abstract

The present disclosure pertains to our discovery that a specialized set of process variables will enable the performance of second layer aluminum metallization of multi-layered semiconductor structures within a single processing chamber, without the need for deposition of a nucleation layer of aluminum, and without the need for a reflow step to fill voids formed during metallization. In general, the improved method of the invention includes the following steps: (a) sputter etching the patterned dielectric surface; (b) depositing at least one continuous wetting layer of titanium over the patterned dielectric surface using ion sputter deposition, the wetting layer having a thickness within the range of about 25 Å to about 200 Å on the sidewall of a contact via formed in the substrate; and (c) depositing a layer of aluminum over the titanium wetting layer using traditional sputter deposition at a substrate temperature within the range of about 380° C. to about 500° C. The substrate temperature is held substantially constant during deposition of the aluminum layer. The deposition rate of the aluminum layer is increased as the deposition progresses, preferably by increasing the target power as the deposition progresses. The method of the invention is particularly useful for second layer metallization of contact vias having aspect ratios up to about 4:1.