Self-Aligned Silicon Nitride-Polyimide Double Step Via Hole
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-05
Composite dielectric layers have been used as passivation layers for integrated circuits in the prior art [*]. The typical composite dielectric layers include a lower layer of silicon nitride on top of which is deposited a layer of polyimide. A problem arises when such composite dielectric layers serve as the insulator layer separating a first metal interconnection layer from a second metal interconnection layer. Where a via hole is to be formed in the composite dielectric layer between the first metal layer and the second metal layer, the relative thickness of the insulator layer creates a substantially large vertical step over which the second metal layer must traverse in order to make electrical contact with the first metal layer.