Importance

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Abstract

A method of forming a dual damascene structure in a semiconductor device arrangement forms a first low k dielectric material over an underlying metal interconnect layer, such as a copper interconnect layer. A nitride etch stop layer is formed on the first low k dielectric layer, and a second low k dielectric layer is formed on the nitride etch stop layer. A via is etched into the first low k dielectric layer, and a trench is then etched into the second low k dielectric layer. The first and second low k dielectric materials are different from one another so that they have different sensitivity to at least one etchant chemistry. Undercutting in the first dielectric layer is thereby prevented during the etching of the trench in the second dielectric layer by employing an etch chemistry that etches only the second low k dielectric material and not the first low k dielectric material.

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First Claim