Semiconductor device with a copper line having an increased resistance against electromigration and a method of forming the same

A method of protecting a copper surface comprising:

• providing a substrate having formed thereon a dielectric layer with a recessed portion and copper structure positioned in the recessed portion, wherein the copper structure has at least one exposed copper surface;
• creating a first reactive plasma environment comprising nitrogen and ammonia;
• exposing the at least one exposed copper surface to the first reactive plasma environment for a first time interval in the range of approximately 20-100 seconds;
• creating a second reactive plasma environment comprising nitrogen, ammonia and a gaseous compound including silicon;
• and
• exposing the at least one exposed copper surface to the second reactive plasma environment, for a second time interval in the range of approximately 3-10 seconds to form a copper/silicon film on the at least one exposed copper surface.

A method of protecting a copper surface comprising:

• providing a substrate having formed thereon a dielectric layer with a recessed portion and copper structure positioned in the recessed portion, wherein the copper structure has at least one exposed copper surface;
• creating a first reactive plasma environment comprising nitrogen and ammonia;
• exposing the at least one exposed copper surface to the first reactive plasma environment for a first time interval in the range of approximately 20-100 seconds;
• creating a second reactive plasma environment comprising nitrogen, ammonia and a gaseous compound including silicon;
• and
• exposing the at least one exposed copper surface to the second reactive plasma environment for a second time interval in the range of approximately 3-10 seconds to form a copper/silicon film on the at least one exposed copper surface, wherein a temperature of said substrate during exposure to the first and second reactive plasma environments is adjusted to approximately 350-420° C., a flow rate of nitrogen is between approximately 4000-10000 sccm during the first and second time intervals, and a flow rate of ammonia is approximately within 100-500 sccm during the first and second time intervals.