Copper CMP evaluation: slurry chemical effect on planarization

As the semiconductor industry drives toward faster circuits, the RC delay due to metalization layers needs to be reduced. Thanks to its low resistivity, copper appears to be a very promising substitute for aluminum in interconnections. In addition, its higher electromigration resistance should lead to greater circuit reliability. However, copper is very difficult to pattern. A damascene process using copper CMP should overcome this issue. This paper is focused on copper CMP evaluation. Two experimental slurries with different oxidizers (one oxygen peroxide based, the other ferric nitrate based) have been evaluated and optimized to improve the planarization effect.