Copper damascene electroplating for efficient CMP

摘要

During damascene interconnect formation, copper is electrodeposited as a continuous film across the seeded dielectric surface of wafers imaged with recessed patterns that define the chip interconnect circuitry. In the next process step, chemical mechanical planarisadon (CMP) is used to remove all metal from the wafer surface leaving the desired Cu circuitry in the recessed dielectric images. To most easily achieve rapid removal of copper and uniform definition of the Cu circuitry, the plated deposit should have a planar surface rather than a topography that depends on the underlying image in the dielectric. In practice, however, the plated copper film is typically recessed over large pads by an amount equivalent to the dielectric thickness, and is relatively thick relative to the field over dense arrays of trenches (Figure 1).