Mask layer and dual damascene interconnect structure in a semiconductor device

A method of forming an interconnect structure using a mask layer deposited over a dielectric material which has been deposited over an underlying interconnect layer, comprising the steps of:

• (a) forming a first mask film over the dielectric material having a known set of etch properties;
• (b) forming a second mask film over the first mask film having a known set of etch properties different from the etch properties of the first mask film;
• (c) forming a third mask film over the second mask film having etch properties substantially identical to the etch properties of the first film;
• and,
• (d) forming a fourth mask film over the third mask film having etch properties substantially identical to the etch properties to the etch properties of the second mask film;
• and
• (e) selectively etching the mask films in multiple steps to form the interconnect structure.

A method of forming an interconnect structure using a mask layer deposited over a dielectric material which has been deposited over an underlying interconnect layer, comprising the steps of:

• (a) forming a via dielectric layer over the underlying interconnect layer,
• (b) forming a trench dielectric layer over the via dielectric layer,
• (c) forming an etch stop layer between the via dielectric layer and trench dielectric layer;
• (d) forming a barrier layer between the via dielectric layer and the interconnect layer;
• (e) forming a first mask film over the dielectric material having a known set of etch properties;
• (f) forming a second mask film over the first mask film having a known set of etch properties different from the etch properties of the first mask film;
• (g) forming a third mask film over the second mask film having etch properties substantially identical to the etch properties of the first film;
• and
• (h) forming a fourth mask film over the third mask film having etch properties substantially identical to the etch properties to the etch properties of the second mask film.