Patent ID: 6350700
Filing Date: 2002-02-26
Classification: H01L

Abstract:
In a process wherein a first photoresist mask is used to form via openings through a first layer of low k dielectric material, followed by removal of said first photoresist mask; and wherein a second photoresist mask is subsequently used to form trenches in a second layer of low k dielectric material corresponding to a desired pattern of metal interconnects for an integrated circuit structure, followed by removal of said second photoresist mask; the improvements which comprise:a) forming a first hard mask layer over an upper layer of low k dielectric material previously formed over a lower layer of low k dielectric material on an integrated circuit structure, said first hard mask layer comprising a material different from said upper and lower layers of low k dielectric material; b) forming, over said first hard mask layer, a first photoresist mask having a pattern of via openings therein; c) etching, through said first photoresist mask, said first hard mask layer to form a first hard mask having said pattern of vias openings replicated therein without etching said layers of low k dielectric material beneath said first hard mask; d) then removing said first photoresist mask; e) forming a second hard mask layer over said first hard mask; f) forming, over said second hard mask layer, a second photoresist mask having a pattern of trench openings therein; g) etching, through said second photoresist resist mask, said second hard mask layer to form a second hard mask having said pattern of trench openings replicated therein without etching said layers of low k dielectric material beneath said first and second hard masks; h) then removing said second photoresist mask; and i) then using said first and second hard masks to form said via openings in said lower layer of low k dielectric material and said trench openings in said upper layer of low k dielectric material; whereby a pattern of via openings and a pattern of trench openings can be respectively formed in layers of low k dielectric material without damage to said low k dielectric material during removal of photoresist masks used respectively in the formation of said respective patterns of via openings and trench openings.