Removal Rate, Uniformity and Defectivity Studies of Chemical Mechanical Polishing of BPSG Films

Wafers where deposited with BPSG films having phosphorus concentration varying from 3.65 to 6.25% and boron concentration varying from 4 to 5.7%. These wafers were polished using CMP and the rates were found to depend on dopant concentrations. A fit to the data indicated that removal rates were more than 3 times as sensitive to boron concentration compared to phosphorus concentration. For a constant phosphorus concentration of 5%, each percent increase in boron increases CMP removal rate by 340 A/min. For a constant boron concentration of 5%, each percent increase in phosphorus increases CMP removal rate by 96 A/min.