Chemical mechanical polishing (CMP) slurry for polishing copper interconnects which use tantalum-based barrier layers

A method of polishing a copper layer having a tantalum-based barrier layer, the method comprising the steps of:

• providing a dielectric layer;
• forming an opening in the dielectric layer;
• forming the tantalum-based barrier layer within the opening;
• forming the copper layer over the tantalum-based barrier layer;
• polishing the copper layer using a first CMP process comprising a carboxylate salt;
• and
• polishing the tantalum-based barrier layer using a second CMP process comprising an amine compound.

A method for forming a copper layer having a tantalum-based barrier layer, the method comprising the steps of:

• forming a first dielectric layer;
• forming a second dielectric layer over the first dielectric layer, the second dielectric layer having a top surface;
• etching an interconnect trench in the second dielectric layer;
• etching a via opening in the first dielectric layer;
• depositing the tantalum-based barrier layer within the interconnect trench and the via opening;
• depositing the copper layer on top of the tantalum-based barrier layer;
• polishing, using a first CMP process, the copper layer to expose a portion of the tantalum-based barrier layer, the first CMP process polishing the copper layer faster than the tantalum-based barrier layer;
• and
• polishing, using a second CMP process different from the first CMP process, the tantalum-based barrier layer to expose the top surface of the second dielectric layer, the second CMP process polishing the tantalum-based barrier layer faster than the copper layer and polishing the tantalum-based barrier layer faster than the second dielectric layer wherein the first CMP slurry is used in conjunction with a first polishing pad and the second CMP slurry is used in conjunction with a second polishing pad wherein the second polishing pad is softer that the first polishing pad.

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

• forming a dielectric layer;
• etching an opening in the dielectric layer;
• depositing a barrier layer within the opening;
• forming a copper-containing conductive material over the barrier layer;
• polishing the copper-containing layer using a first chemical mechanical polihsing (CMP) process that uses a first CMP pad on a CMP processing tool;
• polishing the barrier layer using a second chemical mechanical polishing (CMP) process that uses a second CMP pad on the CMP processing tool;
• and
• polishing a top surface of the dielectric layer using a third chemical mechanical polihsing (CMP) process that uses a third CMP pad on the CMP processing tool.