Method to create super secondary grain growth in narrow trenches

A method for filling a structure with copper, the method comprising the steps of:

• etching an opening in a layer of a dielectric material, whereby a structure selected from the group consisting of a trench and a via is formed;
• depositing or forming a barrier layer in said opening for preventing copper diffusion into said dielectric material;
• filling said opening by depositing copper in an electrochemical deposition or electrochemical plating process onto said barrier layer;
• depositing a further copper layer by physical vapor deposition directly upon said electrochemically deposited copper;
• performing a thermal treatment for inducing recrystallization of said physical vapor deposition deposited copper, whereby recrystallization is also induced in said electrochemically deposited copper;
• and
• removing a copper overburden.