Air Gap Structures from Copper and Low k Damascene

摘要

Air gap structures were fabricated by etching out low k dielectric from between damascene-fabricated copper lines. The void fraction was enhanced by an additional process step designed to increase the aspect ratio of the gap formed by the etch. Damage to the copper lines noted in previous work is described in this work for a typical fluorine dry etch. Comparing capacitance, resistance, and leakage of the air gap structures and the porous low k structures from which they were made, the air gap structures were found to perform better. Breakdown voltage performance was similar on structures with three different dielectric barrier films, and a control wafer without dielectric barrier.