Method to eliminate copper hillocks and to reduce copper stress

A method for the creation of a copper interconnect, comprising steps of:

• providing a substrate;
• depositing a first layer of dielectric over said substrate;
• patterning and etching said first layer of dielectric, creating at least one opening in the surface thereof;
• depositing a layer of barrier material over said first layer of dielectric, thereby including inside surfaces of said at least one opening;
• depositing a layer of copper over said layer of barrier material;
• polishing said layer of copper down to said layer of barrier material, creating a first copper interconnect;
• stimulating stress release in the copper interconnect and therewith stimulating the formation of copper hillocks over the surface of the copper interconnect by annealing said copper interconnect, thereby preventing formation of hillocks during additional high temperature processing of said copper interconnect;
• and
• removing the copper hillocks by polishing said layer of barrier material down to aid first layer of dielectric, thereby polishing said first copper interconnect, thereby additionally removing the first copper interconnect from above a plane of the surface of the first layer of dielectric, thereby assuring additional removal of first copper interconnect irregularities close to the surface of the first copper interconnect, thereby further improving planarity of the first copper interconnect and further decreasing potential formation of copper hillocks over the first copper interconnect.

A method of creating and removing hillocks in a copper interconnect, comprising step of:

• creating a copper interconnect in a first layer of dielectric, a plane of the surface of said copper interconnect being removed from a plane of a surface of said first layer of dielectric by a distance;
• creating hillocks in said copper interconnect by applying a thermal anneal to said copper interconnect;
• and
• removing said hillocks in said copper interconnect by reducing said distance to zero, thereby removing the copper interconnect from above the plane of the surface of the first layer of dielectric, thereby assuring additional removal of copper interconnect irregularities close to the surface of the copper interconnect, thereby further improving planarity of the copper interconnect and further decreasing potential formation of copper hillocks over the copper interconnect.