Method for reducing stress-induced voids for 0.25m&mgr; and smaller semiconductor chip technology by annealing interconnect lines and using low bias voltage and low interlayer dielectric deposition rate and semiconductor chip made thereby

Abstract

A method for making 0.25 micron semiconductor chips includes annealing the metal interconnect lines prior to depositing an inter-layer dielectric (ILD) between the lines. During annealing, an alloy of aluminum and titanium forms, which subsequently volumetrically contracts, with the contraction being absorbed by the aluminum. Because the alloy is reacted prior to ILD deposition, however, the aluminum is not constrained by the ILD when it attempts to absorb the contraction of the alloy. Consequently, the likelihood of undesirable void formation in the interconnect lines is reduced. The likelihood of undesirable void formation is still further reduced during the subsequent ILD gapfill deposition process by using relatively low bias power to reduce vapor deposition temperature, and by using relatively low source gas deposition flow rates to reduce flow-induced compressive stress on the interconnect lines during ILD formation.