Low Erosion Tungsten CMP Process with High Productivity

The erosion generated by the over-polishing step of tungsten CMP (chemical mechanical polishing) may cause metal residue in the surface of upper copper (Cu) damascene interconnects. Generally, lower downforce is effective to decrease the erosion. However, the throughput of W CMP decreases, since the low downforce polishing requires a longer polish time. In this paper, a W CMP procedure with low erosion and high productivity is discussed focusing on differences in incubation times. The procedure contains two polishing steps: shortening the incubation time and suppressing erosion in the over-polishing stage.