Process for forming trenches and vias in layers of low dielectric constant carbon-doped silicon oxide dielectric material of an integrated circuit structure

Abstract

A dual damascene type of structure of vias and trenches formed using layers of low k dielectric material is disclosed, and a process for making same without damage to the low k dielectric material during removal of photoresist masks used respectively in the formation of the pattern of via openings and the pattern of trench openings in the layers of low k dielectric material. Damage to the low k dielectric material is avoided by forming a first layer of low k dielectric material on an integrated circuit structure; forming a first hard mask layer over the first layer of low k dielectric material; forming over the first hard mask layer a first photoresist mask having a pattern of via openings therein; and then etching the first hard mask layer through the first photoresist mask to form a first hard mask having the pattern of vias openings replicated therein, using an etch system which will also remove the first photoresist mask. The first photoresist mask (the via mask) is, therefore, removed during the formation of the first hard mask, instead of in a separate oxidizing step which would damage the low k dielectric material. Damage to the low k dielectric material during removal of the second photoresist mask (the trench mask) is also avoided by depositing a second layer of low k dielectric material over the first hard mask; forming over the second layer of low k dielectric material a second hard mask layer; forming over the second hard mask layer a second photoresist mask having a pattern of trench openings therein; and then forming the second hard mask by etching the second hard mask layer through the second photoresist resist mask to form a second hard mask having the pattern of trench openings replicated therein, using at etch system which will also remove the second photoresist mask. Thus, the second photoresist mask (the trench mask) is also removed during the formation of the second hard mask, instead of in a separate oxidizing step which would damage the low k dielectric material.