The Effect of Contact Implants on the Patterning of Tungsten Damascene Interconnects

Contact implants can increase the etch rate of BPSG during HF precleans used prior to metallization. As a result, troughs form in the implanted BPSG that can trap metal and cause leakage between interconnects. It is shown that the increase in HF etch rate is especially pronounced for BF2 implants, due to the presence of F. The topography, and hence the leakage, can be reduced by capping the BPSG with an undoped oxide prior to implantation.